Product Costing and Activity Based Costing

Process Costing – Scenario

Process costing is used for continuous, mass production where products move through sequential stages. Costs are accumulated by process or department and then averaged over equivalent units – a measure that expresses partially completed units in terms of fully completed units.

The core problem: Profit vs. cash

In the scenario, the CEO (Monica) sees a profit increase of 15% but the bank has only Rs. 2 lakhs after spending Rs. 80 lakhs. The profit statement shows only Rs. 55 lakhs in expenses. The missing Rs. 25 lakhs is tied up in inventory – raw materials, work‑in‑progress (WIP), and finished goods. Inventory value increased by Rs. 25 lakhs, explaining why profit looks healthy while cash is tight.

Exam tip: Profit is not cash flow. In a manufacturing firm, costs incurred to produce unsold units are capitalised as inventory on the balance sheet, not expensed. Only when units are sold do those costs flow to the income statement as cost of goods sold (COGS).

Equivalent units – The key to valuing WIP

To assign costs to partially completed products, we convert physical units into equivalent units (EUs) – the number of fully completed units that would have consumed the same input.

Worked example

Order 804: 2,000 units, currently 70% complete.

$\text{Equivalent units} = 2{,}000 \times 0.70 = 1{,}400 \text{ EUs}$

The costing system values this order by charging the cost of 1,400 equivalent units, not 2,000.

Why equivalent units matter

• They enable accurate valuation of work‑in‑progress on the balance sheet.
• They determine how much cost is allocated to finished goods vs. WIP.
• A build‑up of WIP increases inventory assets but does not affect profit (costs are deferred until sale).

The real‑world mess: Frequent order changes

Marketing can change orders mid-production, causing:

• Overtime work
• Accumulation of semi‑finished goods at various stages
• A bloated inventory that hides cash‑flow problems

This illustrates a classic process costing challenge: when product mix changes, the costing system must still track costs accurately through each stage.

Diagram: How costs flow in process costing

Key takeaways

• Process costing accumulates costs by department/process and averages over equivalent units.
• Equivalent units convert partial completion into a common measure = physical units × % completion.
• Profit can rise while cash falls when inventory (WIP + finished goods) increases – costs are not yet expensed.
• Frequent order changes cause WIP build‑up, complicating cost tracking and valuation.
• Valuing semi‑finished products requires accurate estimation of completion percentage for materials, labour, and overhead.

Methods of Product Costing

Product costing assigns costs to output units (products or services). Two broad approaches exist, each suited to the production environment.

Job Costing vs. Process Costing

• Job costing tracks direct materials, direct labour, and overhead to each distinct job. The unit cost = total job cost ÷ number of units in that job.
• Process costing averages costs over identical units produced in a period. Unit cost = total process cost ÷ total output.

Variations of the Two Methods

Both basic methods have specialised variants:

Customer Costing (Job Costing variant)

Firms with a few large customers allocate costs to each customer account (like a job) to determine profitability per customer.

Batch Costing (Process Costing variant)

Used when identical units are produced in batches (e.g., pharmaceutical tablets, packaged foods, FMCG). Costs are accumulated per batch and then averaged per unit.

Operating Costing (Process Costing variant)

Applied to service operations that deliver a standardised output (e.g., railway services, utilities). Costs are averaged over a service unit (e.g., passenger-km, kilowatt-hour).

Key takeaways

• Job costing is for unique, custom orders; process costing for mass‑produced identical goods.
• Variants: Customer costing (job costing for big clients), Batch costing (process costing by batch), Operating costing (process costing for standardised services).
• The choice depends on production type — not industry alone but whether outputs are distinct or homogeneous.
• All methods ultimately compute a cost per unit, but the accumulation path differs.

Job Costing: Core Concepts

Job costing treats each customer order (a job) as the cost object. The cost accountant opens a job cost sheet the moment an order is received, assigns a unique job code (encoding product, customer, period, serial number), and accumulates all costs against that code.

Direct and Indirect Costs

Prime cost = direct material + direct labour + direct expenses. Conversion cost = total cost − direct material cost (i.e., labour + overheads).

The Job Cost Sheet

A template that summarises:

• Job details: customer, start/completion dates, description, job code.
• Cost breakdown: material, direct labour, direct expenses, indirect costs (often classified into indirect material, indirect labour, factory overhead, administrative overhead).
• Total cost, unit cost (cost per unit produced).
• Profit markup (often based on cost or conversion cost) → final price.

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Variations of Job Costing

The three methods differ in whether direct costs and indirect costs are recorded at actual or budgeted (standard) values.

Normal Job Costing

$\text{Direct costs} = \text{actual}$ $\text{Indirect costs} = \text{budgeted rate} \times \text{actual activity}$

Budgeted rate is computed at the start of the period: $\text{Budgeted indirect rate} = \frac{\text{Total budgeted indirect cost}}{\text{Total budgeted allocation base}}$

• Advantage: Job cost can be computed as soon as the job finishes (e.g., 4th–17th of month) without waiting for month-end actual overheads.
• Used for: Routine decision-making, pricing, performance evaluation.

Example: Budgeted indirect cost = ₹1,00,000; budgeted machine hours = 200. Rate = ₹1,00,000 / 200 = ₹500 per machine hour. A job using 10 machine hours gets ₹5,000 of indirect cost charged.

Actual Job Costing

$\text{Both direct and indirect costs} = \text{actual}$

• Advantage: No variance between costs incurred and costs charged.
• Disadvantage: Must wait until the end of the period to know actual indirect costs → cost information is delayed.
• Used for: Year-end reconciliation, financial accounting (accuracy).

Standard Job Costing

$\text{Both direct and indirect costs} = \text{budgeted (standard)}$

• Advantage: Cost can be computed before the job starts.
• Used for: Planning, quoting a price in response to customer tenders.

Comparison Summary

Exam tip: Memorise the three pairs (“actual–budgeted” for normal; “actual–actual” for actual; “budgeted–budgeted” for standard). The key exam point is the timeliness vs. accuracy trade-off.

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Worked Example: Garment Manufacturer (Job Cost Sheet)

A job produces 300 pairs of shirt and pant. The job cost sheet reports:

From this:

• Cost per pair = ₹949
• Direct material per pair = ₹1,20,000 / 300 = ₹400
• Conversion cost per pair = ₹949 − ₹400 = ₹549 (includes labour + overheads)

Pricing: 60% markup on conversion cost

$\text{Profit per pair} = 60\% \times \text{Conversion cost} = 0.60 \times 549 = \text{Rs. }329$

$\text{Selling price per pair} = \text{Total cost per pair} + \text{Profit} = 949 + 329 = \text{Rs. }1,278$

Price per set (pair of shirt and pant) = ₹1,278

Exam tip: The definition of conversion cost may vary by company. Here, it is total cost less direct material cost. Always check the context.

Key Takeaways

• Job costing tracks costs for individual customer orders using a job cost sheet.
• Prime cost = direct material + direct labour + direct expenses; conversion cost = total cost – direct material.
• Three costing methods differ in the use of actual vs. budgeted costs: Standard (budgeted/budgeted) for planning; Normal (actual/budgeted) for timely decisions; Actual (actual/actual) for accurate reconciliation.
• Indirect costs are allocated using predetermined rates (e.g., ₹500 per machine hour) to assign overheads to jobs before period-end.
• Pricing can be based on a markup on conversion cost (e.g., 60%) or on total cost.

Customer Costing

Customer costing extends job costing by treating the customer as a cost object alongside the job. It aggregates all costs incurred to serve a specific customer (across all jobs for that customer) and computes total customer cost. The goal is to measure and rank customer profitability and to understand why profitability varies across customers.

Why customer profitability differs

Customers place orders differently — in terms of order size, number of deliveries, number of designs, product variety, and special handling. When indirect costs are spread uniformly (e.g., as a percentage of direct cost or variable cost), customers who demand more services subsidise those who demand few. This hidden cross-subsidy distorts pricing and profit measurement.

Worked example: United Leather

United Leather manufactures leather products and garments to customer order. Pricing policy: 100% markup on variable cost (i.e., selling price = 2 × variable cost). Indirect costs are 30% of direct cost at the firm level. The firm was profitable overall, but sales grew 10% while profit grew only 3%. Investigation revealed indirect costs rose 30% (from ₹3M to ₹3.8M) in the same period, driven by increasing variation in customer orders.

Customer order data (selected)

Data shows large variation in order complexity was not reflected in pricing.

Activity-based indirect cost rates

Cost accountant identified four indirect cost pools and computed rates:

Using these rates, indirect costs per customer were recalculated. Leatherite's total indirect cost was 2× that of Radiant Leathers, despite similar revenue.

Revised customer profitability

Exam tip: The key insight: if indirect costs are allocated by a simple rate (e.g., % of direct cost), customers with high service demands appear profitable but are actually low-margin. Activity-based customer costing reveals the true cost-to-serve.

Disciplining customers: pricing based on cost drivers

Once true costs are known, the firm can:

1. Quote prices that include indirect costs based on each customer's order characteristics.
2. Offer lower prices to low-service customers (e.g., Radiant gets a price cut).
3. Raise prices for high-service customers (e.g., Zenith sees a price increase).
4. Encourage customers to modify order patterns (fewer designs, fewer deliveries), shifting to a lower-cost service level.

Some customers may leave; the firm rebalances its customer portfolio toward more profitable ones.

When customer costing is needed

• B2B markets with customised orders.
• Examples: garment manufacturers, automobile ancillary firms, pharmaceutical sub-contractors.
• Any firm where customers vary in order size, design complexity, delivery frequency, or special handling.

Key takeaways

• Customer costing = extending job costing to the customer level; pools all job costs per customer.
• Profitability differs because customers demand different levels of service (designs, deliveries, pieces).
• Traditional overhead allocation hides cross-subsidies: high-service customers appear profitable, low-service customers appear less profitable.
• Activity-based cost rates (per order, per design, per piece) reveal true cost-to-serve.
• Pricing should reflect cost drivers; this disciplines customers and rebalances the portfolio.
• Customer costing is essential in customised B2B manufacturing.

Process Costing

Process costing is used when identical products or services are produced in a continuous flow (process industries). Examples: cement, fertilizer, steel, automobile manufacturing; process-oriented services include banking, insurance, postal services. The goal: compute cost per unit by dividing total process cost by output.

Single Process, No Work-in-Process

Simplest case: a single product, single process (e.g., rice noodles). All activities (mixing, threading, steaming, packing) are grouped as one process. Direct costs (material, labour, machine) are collected; indirect costs are allocated by weight or process hours.

$\text{Cost per unit} = \frac{\text{Total cost}}{\text{Output of period}}$

No work-in-process (WIP) simplifies calculation.

Introducing Work-in-Process: Equivalent Units

When processes span hours or days, some units are incomplete at period-end. We must value closing work-in-process before computing finished‑unit cost.

Equivalent units (EU) convert partially completed units into an equivalent number of fully completed units. Compute separately for each cost element (material, conversion cost).

$\text{EU} = \text{Completed units} + (\text{WIP units} \times \%\text{ completion})$

Key assumption: All materials are added at the start of the process. Conversion costs (labour, overhead) are incurred uniformly.

Worked Example – Single Process (Industrial Coating)

Step 1: Equivalent units

Step 2: Cost per equivalent unit

$\text{Material cost per EU} = \frac{26,000,000}{26,000} = \text{Rs. }1,000$ $\text{Conversion cost per EU} = \frac{10,000,000}{23,200} \approx \text{Rs. }431.03$

Step 3: Cost per finished unit

$\text{Cost per unit} = \text{Rs. }1,000 + \text{Rs. }431.03 = \text{Rs. }1,431.03$

Step 4: Value of closing WIP

• Material: $4,000 \text{ EU} \times \text{Rs. }1,000 = \text{Rs. }4,000,000$
• Conversion: $1,200 \text{ EU} \times \text{Rs. }431.03 \approx \text{Rs. }517,236$
• Total WIP: ₹4,517,236

Reconciliation: Total cost accounted = (22,000 units × ₹1,431.03) + ₹4,517,236 ≈ ₹36,000,000 ✓

Exam tip: The weighted average method (used above) ignores the % completion of opening WIP – it averages all costs (opening + current) over total EU. For FIFO, you must separate opening WIP completion, but it's less common.

Multiple Processes: Inter‑Department Transfers

Most process industries have several sequential processes. Output of one process becomes input (material) for the next. Example: Mars Textile – knitting → dyeing → finishing → etc. Materials may be added at different stages.

We analyse each department separately, using the same EU logic, but the transferred‑in cost from the previous department is treated as a material cost.

Worked Example – Knitting and Dyeing Departments

Knitting Department

EU:

• Material: $1,800 + (300 \times 100\%) = 2,100$
• Conversion: $1,800 + (300 \times 30\%) = 1,890$

Cost per EU:

• Material: $504,000 / 2,100 = \text{Rs. }240$
• Conversion: $149,000 / 1,890 ≈ \text{Rs. }78.84$
• Cost per kg of knitted cloth: ₹240 + ₹78.84 = ₹318.84

Closing WIP (knitting):

• Material: $300 \times \text{Rs. }240 = \text{Rs. }72,000$
• Conversion: $90 \times \text{Rs. }78.84 ≈ \text{Rs. }7,096$
• Total WIP: ₹79,096

Dyeing Department

Receives 1,800 kg of knitted cloth at ₹318.84/kg = ₹573,912. Also adds dye chemicals worth ₹200,000 during the month.

EU (material): $1,750 + (80 \times 100\%) = 1,830$ EU (conversion): $1,750 + (80 \times 60\%) = 1,798$

Cost per EU:

• Material: $782,912 / 1,830 ≈ \text{Rs. }427.82$
• Conversion: $65,400 / 1,798 ≈ \text{Rs. }36.37$
• Cost per kg of dyed cloth: ₹427.82 + ₹36.37 = ₹464.19

Value added in dyeing: ₹464.19 – ₹318.84 = ₹145.35 per kg

Closing WIP (dyeing):

• Material: $80 \times \text{Rs. }427.82 ≈ \text{Rs. }34,226$
• Conversion: $48 \times \text{Rs. }36.37 ≈ \text{Rs. }1,746$
• Total WIP: ₹35,972

Reconciliation check: total cost = cost of finished dyed cloth (1,750 × ₹464.19 = ₹812,333) + closing WIP (knitting ₹79,096 + dyeing ₹35,972) = ₹927,401 – matches opening WIP + all costs incurred (knitting + dyeing). ✓

Exam tip: In multi‑process costing, always compute transferred‑in cost per unit from the previous department and treat it as a material cost for the current department. The value added in each process is the difference between its output cost and the input cost.

Key Takeaways – Process Costing

• Process costing applies to mass production of identical units; cost per unit = total cost ÷ equivalent output.
• Equivalent units convert WIP into finished‑unit equivalents, computed separately for material and conversion cost.
• Weighted average method combines opening and current costs, ignoring opening WIP’s completion percentage.
• Materials added at start → material EU = finished + full WIP; uniform conversion → conversion EU = finished + (WIP × % complete).
• For multiple processes, transfer costs carry forward; each department calculates its own EU and cost per unit.
• Reconciliation (total cost = cost of finished goods + closing WIP) confirms calculation accuracy.

Treatment of Process Losses

Process losses—wastage, evaporation, defective units—are inevitable in manufacturing. How these losses are accounted for depends on whether they are normal (expected under efficient operations) or abnormal (unexpected, avoidable). The core principle: normal loss cost is absorbed into the product (spread across good and WIP units); abnormal loss cost is separated and charged as a period cost.

Normal vs. Abnormal Loss

Worked Example: Paint Manufacturer

Given data

• Input: 100 litres @ ₹100/litre → Material cost = ₹10,000
• Conversion cost = ₹8,000
• Output: 60 litres finished, 35 litres WIP, 5 litres lost
• WIP: 100% complete for materials, 40% complete for conversion
• Selling price = ₹250/litre

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Case 1: Loss treated as Normal

Equivalent units (EU) – lost units are excluded:

Cost per EU:

$$\text{Material cost per EU} = \frac{10,000}{95} \approx 105.26$$ $$\text{Conversion cost per EU} = \frac{8,000}{74} \approx 108.11$$ $$\text{Total cost per EU} = 105.26 + 108.11 = 213.37$$

Allocation:

Profit: Sales (60 × ₹250) = ₹15,000 − Cost of sales ₹12,802 = ₹2,198

The cost of normal loss (₹1,006 implicit) is buried: part goes into WIP, deferring a portion of the loss to the next period.

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Case 2: Loss treated as Abnormal (assumed at end of process)

Equivalent units – lost units are included (100% complete for both material and conversion at detection point):

Cost per EU:

$$\text{Material cost per EU} = \frac{10,000}{100} = 100$$ $$\text{Conversion cost per EU} = \frac{8,000}{79} \approx 101.27$$ $$\text{Total cost per EU} = 100 + 101.27 = 201.27$$

Allocation:

Profit: Sales = ₹15,000 Cost of sales = ₹12,076 Profit before abnormal loss = ₹2,924 Less: Abnormal loss (period cost) = ₹1,006 Profit after abnormal loss = ₹1,918

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Comparison of Methods

Exam tip: Under the normal loss method, a portion of the loss cost is shifted to WIP inventory, inflating current period profit. Managers may prefer this to window-dress earnings. A well-designed costing system must clearly define what constitutes normal loss to prevent manipulation.

Managerial Implications

• Behavioural bias: Managers tend to classify losses as normal to defer costs and boost current profit.
• Cost accountant’s role: Set objective criteria (e.g., % yield, industry benchmarks) for distinguishing normal vs. abnormal loss.
• Reliability of accounting: Inventory valuation choices directly affect profit; misuse can lead to accounting fraud, especially in multi‑product, multi‑process environments.

Key Takeaways

• Normal loss cost is absorbed into good units and WIP; abnormal loss is charged as a period cost.
• Equivalent units calculation differs: exclude normal loss units; include abnormal loss units (if detected at end of process).
• Normal loss treatment results in higher current profit and higher WIP value compared to abnormal loss treatment.
• The distinction between normal and abnormal must be clearly defined to ensure accurate cost measurement and prevent earnings manipulation.

Joint and By‑Product Costing

Many process industries (oil refining, sugar, paper, dairy) produce multiple outputs from a single joint process. These outputs are classified by their economic value:

• Joint products – significant sales value (e.g., diesel, sugar).
• By‑products – low sales value relative to the main products (e.g., molasses).
• Scrap – negligible value, often discarded or sold for trivial revenue.

The crucial accounting problem: how to split the common (joint) cost incurred before the split‑off point among the different products.

Split‑off point – the stage in production where separate products emerge and can be identified.

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Methods for Allocating Joint Costs

Four approaches rest on different rationales.

1. Physical Quantity Method

Allocate joint cost in proportion to the physical output (kg, litres, etc.). Formula:

$$\text{Cost allocated to Product } i = \frac{\text{Quantity of } i}{\text{Total quantity}} \times \text{Total joint cost}$$

Requires all outputs to be measurable in the same unit. Can be misleading if weights differ drastically (e.g., bagasse vs. sugar juice).

2. Sales Value at Split‑off Method

Allocate joint cost in proportion to the market value of each product at the split‑off point.

$$\text{Cost allocated to Product } i = \frac{\text{Sales value of } i \text{ at split‑off}}{\text{Total sales value at split‑off}} \times \text{Total joint cost}$$

Most widely used – reflects the “ability to bear” cost.

3. Estimated Realizable Value (NRV) Method

When a product cannot be sold at split‑off (requires further processing), use its net realisable value:

$$\text{NRV}_i = \text{Ultimate sales value} - \text{Additional processing costs after split‑off}$$

Allocate joint cost using NRV instead of immediate sales value.

4. Constant Profit Margin Method

Determine the overall profit margin (%) on total sales, then apply the same margin to each product’s sales to derive its total cost (including further processing). This ensures equal profitability across products.

$$\text{Overall profit margin} = \frac{\text{Total sales} - \text{Total costs}}{\text{Total sales}}$$ $$\text{Total cost of Product } i = \text{Sales of } i \times (1 - \text{Overall profit margin})$$

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Worked Example: Superfine Chemical

Data

• Raw material: 1,000 kg at total cost ₹5 million
• Process expenses: ₹10 million → Joint cost = ₹15 million
• Output: C1 = 600 kg, C2 = 400 kg
• C1 sold at split‑off: ₹20,000 /kg → sales ₹12 million
• C2 further processed (cost ₹2 million) then sold: ₹30,000 /kg → sales ₹12 million
• Total sales = ₹24 million; Total costs = ₹15 M + ₹2 M = ₹17 M

Allocation Calculations

Method 1 – Physical Quantity Ratio: 600 : 400 = 3 : 2 Joint cost split: C1 = $\frac{3}{5}\times 15 = \text{Rs. }9\text{\,M}$; C2 = $\frac{2}{5}\times 15 = \text{Rs. }6\text{\,M}$ C2 total = 6 + 2 = ₹8 M Unit costs:

• C1: $\frac{9\,000\,000}{600} = \text{Rs. }15\,000/\text{kg}$
• C2: $\frac{8\,000\,000}{400} = \text{Rs. }20\,000/\text{kg}$

Method 2 – Sales Value at Split‑off Sales values: C1 = ₹12 M; C2 = ₹12 M (at split‑off point, though C2 is not yet saleable, we use its eventual sales value as if it were realised at split‑off). Ratio 1 : 1. Joint cost: C1 = ₹7.5 M; C2 = ₹7.5 M C2 total = 7.5 + 2 = ₹9.5 M Unit costs:

• C1: $\frac{7.5\,000\,000}{600} = \text{Rs. }12\,500/\text{kg}$
• C2: $\frac{9.5\,000\,000}{400} = \text{Rs. }23\,750/\text{kg}$

Method 3 – Estimated Realizable Value (NRV) C1 sold at split‑off: NRV₁ = ₹12 M C2: NRV₂ = Sales ₹12 M – Additional cost ₹2 M = ₹10 M Ratio 12 : 10 = 6 : 5. Joint cost allocation:

• C1: $\frac{12}{22}\times 15 = \text{Rs. }8.1818\text{\,M}$
• C2: $\frac{10}{22}\times 15 = \text{Rs. }6.8182\text{\,M}$ C2 total = 6.8182 + 2 = ₹8.8182 M Unit costs:
• C1: $\frac{8.1818\,M}{600} = \text{Rs. }13\,636/\text{kg}$
• C2: $\frac{8.8182\,M}{400} = \text{Rs. }22\,045/\text{kg}$

Method 4 – Constant Profit Margin Overall profit margin: $\frac{24\,-\\,17}{24} = \frac{7}{24} = 29.1667\%$ For each product: Total cost = Sales × $(1 - 0.291667)$ = ₹12 M × 0.708333 = ₹8.5 M Unit costs:

• C1: $\frac{8.5\,M}{600} = \text{Rs. }14\,167/\text{kg}$
• C2: $\frac{8.5\,M}{400} = \text{Rs. }21\,250/\text{kg}$

Comparison of Unit Costs (₹/kg)

Exam tip: The sales‑value and NRV methods are most defensible because they reflect economic value. Physical quantity can produce absurd allocations (heavy, low‑value output absorbs most cost). The constant‑profit method is valid only if the same profit margin on sales is desired.

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Special Cases: By‑products and Scrap

• By‑products – allocate joint cost using the sales value method (i.e., deduct the by‑product’s net revenue from the joint cost before allocating to main products).
• Scrap – not separately costed; scrap revenue is either credited to production overhead or shown as other income.

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Key Takeaways

• Joint costs arise from a single process producing multiple outputs; they must be allocated for inventory valuation and pricing.
• The split‑off point is the moment of separation; costs after that are traceable directly to individual products.
• Four allocation methods exist: physical quantity, sales value at split‑off, NRV, and constant profit margin.
• Sales value at split‑off is the most common; NRV is used when further processing is needed.
• By‑products are typically valued at net realisable value; scrap is not costed.
• The choice of method significantly affects unit costs (as seen in the example) and hence inventory valuation and reported profit.

The Problem with Traditional Costing

Traditional costing allocates overhead (indirect costs) to products using a single, volume-based allocation base — typically machine hours (or direct labor hours). The formula is simple:

$\text{Overhead rate} = \frac{\text{Total estimated overhead}}{\text{Total estimated machine hours}}$

Each product then receives overhead = rate × its actual machine hours.

Why it fails with product diversity

When a company moves from a single standardized product to many customized, low-volume products, overhead costs often skyrocket (e.g., more setups, more inspections, more order processing). Traditional costing continues to spread all overhead evenly across machine hours. Two problems arise:

1. Customized products – They consume a disproportionate share of overhead (extra engineering, frequent changeovers, small batch sizes) but incur only a proportional share of machine-hour-driven overhead. Result: they are under‑costed.
2. Standard/generic products – They run in long, stable production runs with few support activities. Yet they absorb a large chunk of the overhead pool simply because they use many machine hours. Result: they are over‑costed.

This phenomenon is called cross‑subsidization – the high‑volume product subsidizes the low‑volume product, distorting reported profitability.

Example scenario

Exam tip: When a firm operates in a multiple‑product, high‑overhead environment, traditional volume‑based allocation nearly always distorts product costs. The symptom: profit does not improve despite strong sales of customized products.

Activity‑Based Costing as a Solution

Activity‑Based Costing (ABC) allocates overhead to products based on the activities that drive costs, not on a single volume measure. It recognises that activities (e.g., machine setup, quality inspection, order processing) consume resources; products consume activities.

ABC process (conceptual flow)

• Step 1: Identify key activities (e.g., setup, material handling, inspection).
• Step 2: Assign overhead costs to each activity pool (cost of resources consumed by that activity).
• Step 3: For each activity, choose a cost driver that best measures how products consume that activity (e.g., number of setups, number of orders, number of inspection hours).
• Step 4: Calculate an activity rate:

$\text{Activity rate} = \frac{\text{Pool cost}}{\text{Total driver quantity}}$

• Step 5: Assign cost to products: Driver quantity per product × Activity rate.

Comparison: Traditional vs. ABC

When ABC is justified

• Overhead is a large proportion of total cost.
• Wide product diversity (different volumes, complexities, batch sizes).
• Traditional costing gives counter‑intuitive profit signals (e.g., “loss‑making” product that seems essential).

Key takeaways

• Traditional overhead allocation using a single volume‑based driver (e.g., machine hours) distorts costs when product diversity exists – larger‑volume products are over‑costed, smaller customized products are under‑costed.
• This leads to cross‑subsidization and poor strategic decisions (e.g., discontinuing a “loss‑making” product that is actually profitable).
• ABC solves this by tracing overhead to activities and using multiple cost drivers that reflect how products actually consume resources.
• Implementing ABC requires identifying activities, building cost pools, and selecting appropriate drivers – but it improves reliability of cost data for planning and decision‑making.
• The symptom of a broken costing system: strong sales but stagnant profits, especially when the product mix shifts toward customized orders.

Indirect Costs (Overhead) and Allocation

Indirect costs (also called overhead) are costs that cannot be directly traced to a single product. Unlike direct costs (e.g., wood, plywood, laminations for a furniture manufacturer), indirect costs (e.g., supervisor’s salary, factory rent, equipment depreciation) must be allocated across multiple products. The accuracy of product costing depends critically on how this allocation is done.

The Allocation Challenge

A firm producing 10 different product types cannot simply split overhead equally—products differ in size, complexity, and resource consumption. The solution is to choose an allocation base (cost driver) that reflects each product’s use of overhead. Common bases include:

• Material cost
• Labour cost
• Machine hours
• Direct labour hours

The overhead rate is then:

$$\text{Overhead rate} = \frac{\text{Total indirect costs}}{\text{Total allocation base}}$$

Each product receives overhead = Overhead rate × Product’s consumption of the base.

Exam tip: The choice of allocation base is the core judgment call. A poor base can distort product costs—especially when overhead is large relative to direct costs.

Why Overhead Matters More Today

With rising automation and flexible manufacturing systems (same machines making multiple products), the proportion of indirect costs has grown. Two examples:

Even service firms face the same allocation problem—software companies allocate common infrastructure, support, and administrative costs to projects or clients.

Key Points for Accuracy

• If indirect costs are small: simple equal distribution or a single base may be acceptable.
• If indirect costs are large: careful selection of allocation bases becomes essential to avoid mispricing products.

Worked Example (Generic)

A factory has ₹1,00,000 total overhead and produces two products:

• Product A: direct material cost ₹10,000
• Product B: direct material cost ₹30,000

Using material cost as the base: Total material base = ₹40,000 Overhead rate = ₹1,00,000 / ₹40,000 = ₹2.50 per ₹1 of material Overhead allocated: A = ₹10,000 × 2.5 = ₹25,000; B = ₹30,000 × 2.5 = ₹75,000

Key Takeaways

• Indirect costs cannot be traced; they must be allocated using a reasoned allocation base.
• Equal splitting is rarely correct—products differ in resource use.
• Automation and flexible systems increase the share of overhead, raising the stakes for accurate allocation.
• Common allocation bases include material cost, labour cost, and machine hours.
• The overhead proportion in real firms (e.g., HUL, Infosys) can be substantial, making allocation a top-tier costing decision.

Method of Indirect Cost Allocation

Indirect costs (overheads) cannot be traced directly to products. The guiding principle for allocation is cause and effect – a product that uses a department’s services should bear a proportionate share of that department’s cost.

Organisation of Manufacturing Support

Key challenge: Service department costs have no direct link to products. The typical solution is to first allocate service department costs to production departments, then allocate production department costs (including their share of service costs) to products.

Self-service (a department providing service to itself) is ignored.

Ranking Service Departments for Allocation

Normal practice: rank service departments by cost (or by proportion of services provided to other service departments) and allocate sequentially – starting either with the smallest cost or the largest cost, or with the department that provides maximum service to other service departments.

Four Methods of Allocation

1. Equal allocation – pool all service costs and split equally among production departments. Simple but ad‑hoc; ignores actual usage.

2. Ratio-based allocation – allocate using a single physical measure (e.g. number of employees or machine hours). Better than equal, but arbitrary if multiple different ratios exist.

3. Step‑wise allocation – allocate service department costs sequentially using estimated percentages of services provided to other departments. Once a department’s costs are allocated, it receives no further allocations from later departments.

4. Simultaneous equations – solve a system of linear equations to account for reciprocal services among service departments. More accurate, but more costly.

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Worked Example: Sunshine Chemicals

Sunshine Chemicals produces two chemicals (X and Y) in two production plants. Three service departments support the plants.

Additional data

• Employees: Maintenance 40, Personnel 10, Accounting 20; Plant X 200, Plant Y 300.
• Machine hours: Plant X 12,000, Plant Y 28,000.

Estimated service usage (from departmental heads)

• Maintenance: 30% to X, 65% to Y, 2% to Personnel, 3% to Accounting.
• Personnel: service directly proportional to number of employees (same basis).
• Accounting: 40% to X, 57% to Y, 2% to Maintenance, 1% to Personnel.

Option 1 – Equal allocation ₹18.5 lakhs to Plant X, ₹18.5 lakhs to Plant Y. Ignores that Plant Y is larger (300 workers vs 200, 28,000 machine hours vs 12,000).

Option 2 – Ratio allocation Ratio of employees (2:3) or machine hours (12:28). Both give different results; no assurance actual usage matches either ratio.

Option 3 – Step‑wise allocation (starting with smallest cost, Personnel first)

1. Allocate Personnel (₹6 lakhs) to Maintenance, Accounting, Plant X, Plant Y using the proportional basis (employees).
2. Allocate Accounting (₹11 lakhs + its share from Personnel) to the remaining departments using its estimated percentages.
3. Allocate Maintenance (₹20 lakhs + its shares from Personnel & Accounting) to Plant X and Plant Y only.

Result: ₹13.20 lakhs charged to Plant X, ₹23.80 lakhs to Plant Y.

Alternative start (largest cost or maximum service to other depts) If we start with Personnel (because it provides 11% of its service to other service depts), then Maintenance (5% to others), then Accounting (3% to others), the final allocation to production departments changes only slightly.

Option 4 – Simultaneous equations Set up equations to fully reciprocate services (e.g., Accounting provides service to Maintenance, Maintenance provides service to Accounting). Solve for true cost of each service department before allocating to production.

Exam tip: Step‑wise allocation is the most common exam method. Be ready to rank service departments by cost or by percentage of service provided to other service departments, then allocate sequentially – stopping when only production departments remain.

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Key Takeaways

• Indirect cost allocation follows cause‑and‑effect; arbitrary bases distort product costs.
• Service department costs are first allocated to production departments; reciprocal services complicate the process.
• Step‑wise allocation is a practical compromise: allocate sequentially, ignoring later reciprocal flows.
• Simultaneous equations give theoretically correct allocation but require more effort.
• Choice of allocation method can significantly affect reported product costs (e.g., ₹13.20 vs ₹18.5 for Plant X in the example).

Misallocation of Indirect Cost

Product cost accuracy hinges on how indirect costs are allocated. A flawed allocation method — however simple — can systematically over-cost some products and under-cost others, leading to disastrous pricing and product-mix decisions.

The core problem: arbitrary allocation bases

Many firms allocate indirect costs using a single, easy-to-measure factor such as procurement cost, number of units, or direct labour hours. The assumption is that higher-cost or higher-volume products should bear more overhead. This assumption is often false, because different products consume support services in very different proportions.

Example 1: Retail — perfume vs. wheat flour

A large retailer centralises procurement and distribution. It pools warehouse, distribution and shop-level expenses, finds they amount to 30% of procurement cost, and adds 30% to every product’s procurement cost to recover overhead. A further 10% profit margin is then added.

Distortion: The perfume is heavily over-costed — it consumes very little warehouse space or handling, yet bears ₹120 of overhead. The wheat flour is under-costed — it requires significant handling but bears only ₹114.

Consequence: The perfume’s price becomes uncompetitive. To move inventory, the shop may offer a 50% discount, turning an apparently profitable product into a loss-maker.

Exam tip: A simple percentage add-on based on procurement cost assumes all products consume support equally. Always check whether the allocation base is correlated with actual consumption of indirect resources.

Example 2: Leatherite — standard vs. customised products

Leatherite started with one standard product (P1) and later added customised products (P2–P4). The original costing system was designed for a single product and allocated overhead at ₹90 per unit to all products, regardless of type.

Original (flawed) profitability

Based on this, a manager would:

• Recommend pushing customised products (they appear profitable).
• De-emphasise P1 (it appears to lose ₹26 per unit).

The hidden distortion

In reality, most overhead (designing, sampling, order processing) is caused by customised products, not the standard product. Further analysis reveals:

• Total overhead = ₹90,000
• Overhead related to P1 = ₹10,000
• Overhead related to P2–P4 = ₹80,000

Assuming comparable volumes, the per‑unit overhead should be:

• P1: ₹20 per unit (instead of ₹90)
• P2–P4: ₹160 per unit (instead of ₹90)

Corrected profitability

Using the accurate allocation:

• P1 now shows a profit (cost = ₹200 + ₹20 = ₹220; market price = ₹264 → profit ₹44).
• P2 and P3 become loss-making (cost = material + ₹160; even with a 20% mark‑up, they may not cover actual overhead).
• P4 may remain profitable depending on its material cost.

Why the original decision backfired: Shifting sales toward customised products increased the total overhead consumed, further reducing overall profit. The wrong cost data caused a self-fulfilling spiral of rising costs and falling margins.

Key takeaways

• Arbitrary allocation bases (cost %, units, labour hours) can severely distort product costs when products differ in how they use support activities.
• Over-costed products become uncompetitive; under-costed products appear falsely profitable, encouraging a product mix that actually increases total indirect costs.
• The two examples show the same trap: using a simple ratio (procurement cost + 30%; ₹90 per unit) ignores causal relationships between products and overhead consumption.
• Correct allocation requires identifying cost drivers — the activities that truly generate indirect costs (e.g., number of setups, hours of design work, weight or volume for transport).
• A flawed costing system not only misstates individual product profitability but can lead managers to make decisions that reduce overall firm profit.

1. Philosophy and Motivating Examples

Activity-Based Costing (ABC) is built on a simple intuition: an organization is a bundle of activities (performed by people, machines, or both). Inputs are transformed through a series of activities into value‑added outputs (products or services). Costing under ABC:

1. Measure the cost of performing each activity.
2. Charge that cost to any product or service that consumes the activity. If a product does not use an activity, it is not charged.

The product cost equals all direct costs (materials, etc.) plus the cost of the activities it consumes.

Motivating Examples

Exam tip: The customer‑order example illustrates how ABC reveals hidden cost consequences of changes in order structure – a key advantage over traditional costing.

Key takeaways

• ABC allocates costs based on actual activity consumption, not arbitrary allocation bases.
• Traditional systems often overcost simple, low‑effort products and undercost complex, high‑effort products.
• ABC can detect profit erosion from changes in batch sizes, delivery schedules, or product mix – information that conventional costing misses.

2. Classification of Activities

ABC divides organisational costs into two broad groups: direct material/input costs (traced directly to the product) and activity costs. Activity costs are further categorised into four levels, each with distinct cost drivers and cost behaviour.

Exam tip: Adding more products increases product‑level costs significantly. Companies like P&G and Apple limit product variety to control these costs; Samsung uses many products to penetrate markets.

Key takeaways

• Four activity levels: unit, batch, product, facility.
• Unit‑level: variable, driven by volume.
• Batch‑level: mixed, driven by number of batches.
• Product‑level: fixed, driven by number of products.
• Facility‑level: fixed, not allocated to products – charged directly to the income statement (used only for cost control and outsourcing decisions).

3. Cost Drivers, Master List, and Bill of Activities

Cost Drivers

For each activity, identify the factor that causes its cost to increase or decrease – the cost driver.

Cost of an activity = (cost per driver unit) × (number of driver units consumed).

Master List of Activities

The final output of an ABC implementation is a Master List of Activities that contains:

• Every activity performed in the organisation.
• Its cost driver.
• The cost of performing the activity per cost driver unit.

From this master list, a Bill of Activities (BOA) can be prepared for each product or service. The BOA lists all activities relevant to that product – analogous to a Bill of Materials (BOM) which lists all materials.

Cost Sheet under ABC

The cost sheet for a product has two broad categories:

1. Material Cost (+ direct inputs)
2. Activity Cost, further grouped into:
   • Unit‑level activities cost
   • Batch‑level activities cost
   • Product‑level activities cost

Facility‑level activities are excluded from the product cost sheet; they are expensed directly.

Application in job‑based manufacturing/services – For customized machines, software, consulting, auditing, etc., having BOM and BOA makes cost estimation easy and accurate.

Flow of ABC Implementation

Key takeaways

• Cost driver links activity cost to consumption. Examples: number of setups, purchase orders.
• Master List of Activities is the central repository: activity, driver, cost per driver.
• Bill of Activities (BOA) lists all activities required for a product – similar to BOM.
• Product cost under ABC = material cost + unit‑ + batch‑ + product‑level activity costs. Facility‑level costs are not included in product cost; they are controlled separately and can be outsourced.

Implementation of Activity Based Costing

Activity Based Costing (ABC) turns costing from a top-down, accounting-department exercise into a decentralized, manager-owned system. Instead of line managers passively accepting overhead rates they don’t trust, ABC makes every departmental head identify, cost, and own the activities in their area. This transparency removes disputes and improves decision-making.

Steps to Implement ABC

1. Form an ABC team of all departmental managers; provide a brief ABC introduction.
2. Each manager lists activities and sub-activities of their department, involving employees. Activities must be distinctive and have a clear output (e.g., Purchase Department: “Preparation of a Tender Document”, “Tendering”, “Comparison of Quotation”, “Vendor Evaluation”, “Preparing Purchase Order”).
3. List resources and time required for each activity.
4. Collect financial data for resources (with help from accounting).
5. Classify activities into four levels:
   • Unit-level (per unit)
   • Batch-level (per batch)
   • Product-level (per product)
   • Facility-level (sustaining the facility)
6. Submit department lists to a central pool → Master List of Activities.
7. Product managers identify activities relevant to their product and prepare a Bill of Activities (BOA).

Master List of Activities

• Jointly owned and maintained by all departmental heads.
• Reviewed quarterly: update activity costs for salary changes, power tariff changes, equipment replacement, or process changes.
• Full annual review of the activity list itself.
• If costing department alone ran ABC, it would require massive manpower – a key reason many firms resist ABC.
• Wrong notion: ABC needs daily actual data. In reality, activities are costed at current budgeted rates; actual data is only needed for cost-plus contracts or control.

Exam tip: ABC is not about actual costing; it uses budgeted activity costs for planning and decision-making. Actual costs are used for control, not as the primary system.

Activity Based Budgeting (ABB)

An extension of ABC: departmental heads provide budgeted activity costs. Budgeting at the activity level improves accuracy. Actual costs can then be compared with budgeted for variance analysis.

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Single-Product Example – Alpha & Co.

Production: 50,000 units/year, sold 42,000 units at ₹2,500/unit.

Traditional Cost Sheet (₹ per unit unless noted)

(Note: Inventory valuation only includes manufacturing costs: material + labour + production overhead = ₹1,600/unit. Admin and S&D overhead are period costs.)

ABC Cost Statement (same total profit)

Why ABC is richer: If batch size changes (e.g., to 7,500 units), managers can recompute batch-level cost per unit; traditional costing has no mechanism to adjust. ABC also reveals the impact of overtime or equipment replacement on specific activities.

Multi-Product Example – Beta & Co. (Pharmaceuticals)

Products: P1 (high-volume mass-consumption, like Crocin) and P2 (low-volume specialized dosage). Same basic ingredients, different dosages/additives.

Traditional Costing – overhead allocation bias Using two bases:

If market price is ₹2,000/kg for P1 and ₹1,500/kg for P2, P1 appears profitable under unit-based allocation but loss-making under machine-hour allocation. Managers can choose the basis that makes their product look good – a fundamental flaw of traditional costing.

ABC removes bias by tracing costs through activities.

Result: P1’s cost remains higher than its selling price of ₹2,000/kg – ABC shows P1 is loss-making regardless of overhead allocation basis. Traditional costing was misleading.

Exam tip: Traditional costing systematically underestimates the cost of low-volume specialized products because it spreads overhead evenly across a single (often volume-based) driver. ABC reveals the true cost by recognising batch- and product-level costs.

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Non-Value Added and Non-Core Activities

ABC encourages managers to scrutinise every activity:

• Non-value added (NVA) activities: Activities that consume resources but do not create value for internal or external customers. These often persist long after their original need disappears.

  • Example: A follow-up team in Purchase Department set up during a material shortage continues even after supply normalises, because the purchase manager’s performance is measured only on on-time delivery – not on cost.
  • Example: Quality control inspects a mature product with zero initial defects, due to inertia.

• Core vs. non-core activities: Senior managers classify activities. Continuous improvement on core activities (quality, cost, time) builds cost leadership and creates entry barriers.

  • Airline example: Ticketing, check-in, on-time arrival, in-flight comfort – when all employees improve these core activities on all three dimensions (quality, cost, time), the airline commands premium market share.

Key takeaways

• ABC is implemented decentrally; departmental managers own their activities.
• Master List of Activities is reviewed quarterly (cost updates) and annually (activity list overhaul).
• ABC avoids the overhead-allocation bias of traditional costing; it objectively assigns costs via activities.
• Traditional costing underestimates low-volume specialised products; ABC corrects this.
• ABC identifies non-value added activities that drain resources without contributing value.
• Continuous improvement of core activities on quality, cost, and time drives competitive advantage.

Activity Based Management (ABM)

Activity Based Management (ABM) is the natural extension of Activity Based Costing (ABC). While ABC's primary goal is to produce reliable cost data, ABM uses that data for planning, decision-making, and control. Intuitively: once you know which activities truly consume resources, you can manage those activities — not just report costs.

Core idea: from costing to managing

Traditional costing aggregates overhead into arbitrary pools (production, admin, selling), obscuring true cost drivers. ABC measures how products/services demand activities, and activities consume resources. ABM then takes that insight and embeds it into three managerial systems:

1. Activity Based Budgeting – Budgets are built from the activities needed, not from last year's functional lines. Those who perform the activities participate in setting the budget, making the process highly decentralized.
2. Activity Based Controlling & Performance Measurement – Actual activity costs are collected; variance reports compare them to activity budgets. But control is not limited to cost — performance is assessed on three dimensions:
   • Time (speed of activity)
   • Quality (defect-free output)
   • Cost (efficiency)
3. ABC-based decision making – Pricing, product mix, process improvement — all decisions use activity-level data.

Example: For the activity "assemble a product", workers are encouraged to simultaneously reduce assembly time, maintain quality, and minimize cost. This triple focus drives continuous improvement.

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Worked example: Creative Furniture – pricing distortion fixed by ABM

Creative Furniture makes three models:

• Model 1: low-cost wood & steel; simple labour; low material cost; activity effort = Rs. 2000
• Model 2: high-end wood & imported steel; similar labour time to Model 1; activity effort = Rs. 3000 (1.5× Model 1)
• Model 3: high-end wood & imported steel + intensive engraving; specialised labour; activity effort = Rs. 15,000 (5× Model 2)

Originally, the company used a 20% profit mark-up on total cost (material + labour + overhead). This created a distorted pricing scheme:

Because material cost drives up total cost, the 20% markup forces customers of high‑material models to pay excessive profit — even though the company's value‑adding activities are modest. Meanwhile, the high‑effort Model 3 is under‑rewarded.

ABM logic: The company exists to add value to inputs (wood, steel). Customers should pay for the cost of input (storage, carrying cost, etc.) plus a profit margin only on the value‑added activities, not on the raw materials. If Model 1's profit is taken as fair, then the desired profit margin on activity cost is 100% (profit = activity cost). Applying this:

• Model 1: Profit = 100% × 2000 = 2000 → revised price = material cost + activity cost + profit on activity.
• Model 2: Profit = 100% × 3000 = 3000 → price lower than original (because high material cost no longer inflates profit).
• Model 3: Profit = 100% × 15000 = 15000 → price higher than original (effort is rewarded properly).

Exam tip: The key insight is that profit should be a reward for effort (activities), not for expensive inputs. ABM corrects the arbitrary link between material cost and profit.

Key takeaways

• ABM extends ABC by using activity cost data in budgeting, control, and decision‑making.
• Performance measurement under ABM covers time, quality, and cost — not just cost.
• Pricing should be based on activity cost plus profit margin on activity, not on total cost including materials.
• High material cost can inflate profit under traditional markup; ABM aligns reward with actual effort.

Purpose of Product Costing

Determine the cost per unit of an end product or service. This cost data underpins pricing, inventory valuation, and profitability analysis.

Job Costing

Job costing suits firms that produce to customer orders. Each job is a distinct cost object.

• Direct costs (materials, labour) are traced to the job on an actual basis.
• Indirect costs (overhead) are charged using a predetermined overhead rate.
• Common costs are pooled under few cost centres and allocated to jobs.

Customer costing extends job costing by tracing costs to individual customers. It reveals profitability differences when customers demand extra services (frequent deliveries, high customisation, specification changes) that job costing may not capture.

Process Costing

Process costing is used in complex, continuous process industries. Key challenges:

• Valuation of work‑in‑process (WIP): semi‑finished products are converted into equivalent units of completed output.
• Joint products and byproducts: common costs incurred up to a split‑off point must be allocated. Allocation bases mentioned include:
  • Unit basis
  • Sales value
  • Net realisable sales value
  • Profit margin
• Process loss:
  • Normal loss (within predetermined tolerance) is distributed across all units produced – including closing WIP – and a portion may be carried to the next period.
  • Abnormal loss is separated and charged against the income of the same period.

Exam tip: Distinguish normal loss (absorbed in product cost, affects future periods through WIP) from abnormal loss (expensed immediately as a period cost).

Why Accuracy Matters

Cost data drives decisions. Allocating common costs is the main source of distortion. Incorrect costs lead to faulty pricing, product mix, and performance evaluation. This motivates alternative costing systems like Activity‑Based Costing.

Key takeaways – Product Costing

• Two fundamental methods: job costing (custom orders) and process costing (continuous production).
• Job costing uses predetermined overhead rates; direct costs are actual.
• Process costing handles WIP via equivalent units, joint costs via allocation methods, and losses via normal/abnormal treatment.
• Customer costing extends job costing to analyse customer‑level profitability.

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Evolution of Costing Systems

Early costing systems focused on simple closing stock valuation for financial reporting. Costs were aggregated at a few levels (production, selling, distribution, administration). With growing product/service variety, these aggregated allocations distorted product costs. Managers made unreliable decisions based on inaccurate data. Activity‑Based Costing (ABC) emerged to address these challenges.

Core Concepts of ABC

ABC treats material cost and activity cost as the two broad categories. It recognises that organisations add value by performing activities; the cost sheet mirrors this value creation.

Activities are classified into four levels:

Applications and Extensions

• Reliable product cost data for decision‑making on pricing, mix, and outsourcing.
• Activity‑Based Budgeting (ABB): planning and budgeting at the activity level.
• Benchmarking: activity analysis allows comparison with other units.
• Performance evaluation: targets set on Quality, Cost, and Time dimensions of activities.
• Activity‑Based Management (ABM): integrating ABC into planning, control, and decision‑making.

Exam tip: ABC improves cost accuracy by tracing overhead to activities rather than using broad allocation bases. Understand the four activity levels and why batch‑level costs may cause traditional systems to over‑ or under‑cost.

Key takeaways – Activity‑Based Costing

• Traditional costing distorts costs when products are diverse and overhead is high.
• ABC classifies costs by activity levels: unit, batch, product, facility.
• ABC supports budgeting (ABB), benchmarking, performance evaluation, and management (ABM).
• Reliable cost data improves pricing, product mix, and strategic decisions.

Exercise 1 & 2: Job Costing for Balu Tailors (Tailoring Shop)

Job costing collects direct costs (easily traced to a specific job) and allocates a fair share of indirect costs (overhead) to each job. The same logic scales from a tailor shop to a software firm or space agency — only the numbers change.

Direct costs per pair (pant + shirt)

Overhead cost per month (existing shop, 5 machines)

Expected monthly volume = 500 pairs Overhead rate per pair = ₹29,375 ÷ 500 = ₹58.75

Standard cost sheet for the order of 200 pairs

Exam tip: The ₹362 price per set is the minimum to recover costs and earn a 40% markup. If the job were non‑standard (e.g., party wear), the stitching time per pair would increase, raising direct labour cost and the price.

What stays the same across industries?

Key takeaways

• Direct costs are traced; indirect costs are pooled and allocated using a rational basis (e.g., machine hours, labour hours, volume).
• Overhead rate = total overhead ÷ total allocation base (e.g., 500 pairs).
• The same three‑step process works for any job: identify direct costs, collect indirect costs, choose allocation basis, compute cost per job.
• Markup is added to total cost to arrive at selling price.
• For non‑standard jobs, estimate direct costs based on estimated time rather than a standard rate.

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Exercise 3: Job Costing for Global HR (Service Firm)

Global HR is a consulting firm. A job is a performance assessment for 50 senior managers. The same cost‑sheet logic applies — only the line items change.

Daily rates of consultants

Corporate overhead rate

• Total corporate overhead: ₹200,00,000 (200 lakhs)
• Total billable days: 25 consultants × 150 = 3,750 days
• Overhead rate per consultant day: ₹200,00,000 ÷ 3,750 = ₹5,333 (rounded)

Job cost sheet: Performance assessment (50 managers)

Price per manager = ₹1,82,40,053 ÷ 50 ≈ ₹3,64,800

Key takeaways

• Service firms use billable days as the allocation base for overhead.
• Direct costs include consultant salaries (or opportunity cost) and travel.
• Markup covers profit and any unallocated risk.
• The cost‑sheet format is identical to the tailor shop — only the numbers differ.

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Exercise 4: Activity‑Based Costing for Trident Electric Motors

Trident makes custom electric motors. Two customers want 4,000 units each, but with very different service demands. The old costing method unfairly penalises the simpler order.

Old costing method (single overhead rate)

• Overhead: ₹20,000 per machine hour (applied uniformly)
• Direct material: ₹200 per unit × 4,000 = ₹8,00,000
• Machine hours required: 200 hours (same for both orders)
• Design charges: ₹2,00,000 per design

Rana Electronics (simpler order) pays ₹150 more per unit under the old method — a cross‑subsidy.

New costing method (activity‑based)

Trident identifies three activity pools and their cost drivers:

For K‑Electronics: 4 deliveries → 4 orders, 4 set‑ups, 4 designs. For Rana Electronics: 1 delivery → 1 order, 1 set‑up, 1 design.

Comparison

Exam tip: Under a single overhead rate, simple orders subsidise complex ones. Activity‑based costing (ABC) uses multiple cost drivers to assign overhead more accurately, enabling competitive pricing for low‑service jobs.

Key takeaways

• Old method used one driver (machine hours) → unfair for orders with different service demands.
• New method uses multiple activity rates (assembly, order processing, set‑up, design).
• ABC gives truer costs: Rana Electronics’ cost drops, allowing a lower competitive price.
• The cost‑sheet structure remains: direct costs + allocated indirect costs. Only the allocation basis becomes more refined.

Job Costing with Multiple Jobs — Exercise 5

Job costing tracks costs individually for each custom order (job). When multiple jobs run simultaneously, each job accumulates its own direct material, direct labor, and overhead. The key challenge is distinguishing completed jobs (→ cost of sales + revenue) from work‑in‑progress (WIP) (→ closing inventory).

Data flow

1. Opening WIP – Costs already incurred on jobs that started in a prior period.
2. Current period increments – Additional material, labor hours, and machine hours spent on each job during the month.
3. Total job cost = Opening WIP + Incremental material + (Incremental labor hours × labor rate) + (Incremental machine hours × predetermined overhead rate).
4. Identify completed jobs – Their total cost becomes cost of sales.
5. Revenue = Total cost of completed jobs × $(1 + \text{markup\%})$ (here 40% markup on cost).
6. Closing WIP = Total cost of jobs not yet completed.

Worked example (Excel Engineering)

Given:

• Labor rate = ₹100 per hour
• Overhead rate = ₹300 per machine hour
• Markup = 40% on total cost

Opening WIP (1 May)

Incremental costs during May

Compute total cost per job (example for Job 132)

• Opening WIP = ₹9,000
• Incremental material = ₹3,500
• Labor = 7 hrs × ₹100 = ₹700
• Overhead = 3 hrs × ₹300 = ₹900
• Total = ₹14,100

Completion status Completed: Jobs 132, 142, 148, 151, 152 Incomplete (still WIP): Jobs 137, 149, 150

For completed Job 132, revenue at a 40% markup is $\text{Rs. }14{,}100\times1.4=\text{Rs. }19{,}740$. Applying the same rule to every completed job gives:

• Cost of sales: ₹73,110
• Revenue: $\text{Rs. }73{,}110\times1.4=\text{Rs. }1{,}02{,}354$
• Closing WIP: ₹25,440, comprising incomplete Jobs 137, 149, and 150

Key takeaways

• Opening WIP + current period costs = total cost to account for.
• Assign costs separately per job using actual material, labor hours (× rate), and machine hours (× overhead rate).
• Markup is applied only to completed jobs when pricing.
• Cost of sales = total cost of finished jobs; closing WIP = total cost of unfinished jobs.
• Keep a clear completion status column to avoid mixing sold and unsold costs.

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Operating Costing for a Transport Company — Exercise 6

Operating costing (or operation costing) is used by service organisations (e.g., transport, hotels). Costs are classified as fixed (per period) or variable (per unit of service – here per trip, per km, per hour). A standard cost sheet helps set the hire charge.

Fixed costs per month (per bus)

Expected operating hours per month = 240 hours Fixed cost per hour = $\frac{2,72,500}{240} = \text{Rs. }1,135$

Fixed cost for an 8‑hour trip = $1,135 \times 8 = \text{Rs. }9,083$

Variable costs

Fuel cost per km

• Mileage = 1.2 km/litre
• Diesel cost = ₹60/litre
• Cost per km = $\frac{60}{1.2} = \text{Rs. }50$

For 80 km (assumed standard distance in 8 hours) → $50 \times 80 = \text{Rs. }4,000$

Standard cost sheet for an 8‑hour, 80‑km trip

Pricing extra services

Additional kilometre

• Incremental cost = fuel per km = ₹50
• After 30% markup → $50 \times 1.3 = \text{Rs. }65$ per extra km.

Additional hour (first approach: full allocation)

• Take fixed cost per hour (₹1,135) plus the full variable salary per trip allocated hourly?
• A full-allocation approach includes fixed cost per hour and can overcharge because most fixed costs do not increase with extra hours.

Revised approach – incremental costing for extra hour Only costs that actually rise per extra hour:

• Driver variable salary (₹500 per 8‑hr block, but if extra hour is within the next full shift? Actually for one extra hour, the same 8‑hr block rate applies for the driver – so the incremental cost is the full ₹700 for any extra hour that triggers a new shift or overtime.
• Only the ₹700 variable salaries are relevant for an extra hour.
• Markup: $700 \times 1.3 = \text{Rs. }910$ per extra hour.

Exam tip: When pricing additional units of service (extra km, extra hour), use incremental (avoidable) costs, not fully‑allocated fixed costs. Fixed costs like depreciation and repairs are sunk for that period.

Competitor comparison

• Our base price is lower; per‑km price is much lower.
• Our initial extra‑hour price (₹1,590) was higher than competitor (₹1,300).
• By switching to incremental cost pricing (₹910), we become competitive on all components.

Key takeaways

• Operating costing separates fixed (period) and variable (per‑unit) costs.
• Fixed costs are spread over expected activity hours.
• Variable costs include fuel (per km) and driver/assistant payments (per trip).
• For standard quotes: total cost + markup.
• For extra services: only incremental variable costs plus markup should be charged.
• Competitor analysis reveals where cost assumptions can be refined.

Process Costing: Weighted Average & Loss Treatment

Process costing averages costs over all units produced in a period. The core challenge: work‑in‑process (WIP) units are only partially complete, so we convert them into equivalent units (EU) – the number of fully completed units they represent for each cost component (material, conversion).

Two methods exist: weighted average (blends opening WIP costs with current period costs) and FIFO (separates opening WIP). The discussion below uses weighted average and then treats normal and abnormal losses.

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Weighted Average Method: Equivalent Units & Cost per EU

Intuition: Under weighted average, we ignore the degree of completion of opening WIP. We treat all units (opening + started) as a single pool. EU = units completed (always 100% complete) + (% completion of closing WIP × closing WIP units). Opening WIP information is irrelevant for EU computation – it only matters when we allocate the total costs.

Exercise 7 – Computing Equivalent Units Only

A process:

• Opening WIP: 30 units (60% material drawn, 20% conversion complete) – not used in weighted average EU.
• Completed during period: 400 units.
• Closing WIP: 60 units (80% material, 60% conversion completed).

EU calculation:

Exam tip: Weighted average never uses opening WIP completion % for EU. Opening WIP costs are added to current costs later, but the EU count only looks at what emerged this period (completed) and what remains (closing WIP at its %).

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Exercise 8 – Full Cost Computation & Reconciliation

Data:

• Opening WIP: 5,000 units (material 100% complete, conversion 40% complete). Costs: material ₹6,00,000, conversion ₹40,000.
• Units started during month: 40,000 units.
• Costs added: material ₹48,00,000, conversion ₹38,00,000.
• Closing WIP: 3,000 units (material 100%, conversion 60%).

Step 1: Physical flow

$\text{Units to account for} = \text{Opening WIP} (5,000) + \text{Started} (40,000) = 45,000$ $\text{Completed units} = 45,000 - 3,000\ (\text{closing WIP}) = 42,000$

Step 2: Equivalent units (weighted average)

Step 3: Total costs (opening + current)

Step 4: Cost per equivalent unit

$\text{Cost per EU (material)} = \frac{54,00,000}{45,000} = \text{Rs. }120$ $\text{Cost per EU (conversion)} = \frac{38,40,000}{43,800} = \text{Rs. }87.67$ $\text{Total cost per EU} = 120 + 87.67 = \text{Rs. }207.67$

Step 5: Cost allocation

• Completed units (42,000 units): Material: $42,000 \times 120 = \text{Rs. }50,40,000$ Conversion: $42,000 \times 87.67 = \text{Rs. }36,82,192$ Total: ₹87,22,192

• Closing WIP (3,000 units, 60% conversion): Material: $3,000 \times 120 = \text{Rs. }3,60,000$ Conversion: $1,800 \times 87.67 = \text{Rs. }1,57,808$ Total: ₹5,17,818

Step 6: Reconciliation

Reconciliation confirms total cost = total allocated. ✅

Key takeaways – Weighted Average Method

• EU ignores opening WIP completion %; only closing WIP % matters.
• Total costs = opening WIP costs + current period costs.
• Cost per EU = total cost ÷ total EU for each component.
• Always reconcile total costs with allocated costs.
• Simple and widely used when opening WIP levels are stable.

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Normal vs Abnormal Loss in Process Costing

Intuition: Not all units survive the process – some are lost (e.g., breakage, evaporation). Losses are either normal (expected, unavoidable within a tolerance) or abnormal (unexpected, avoidable). The accounting treatment differs fundamentally:

• Normal loss is absorbed into the cost of good units – no separate loss cost is recognised. The total cost is spread over fewer good units, raising their cost.
• Abnormal loss is isolated as a separate cost item, charged directly to the Profit & Loss account – making the loss visible for investigation.

Exercise 9 – Comparing Normal & Abnormal Loss Treatment

Data (furniture manufacturer):

• Opening WIP: 200 units (material 100% complete, conversion 60% complete). Costs: material ₹60,000, conversion ₹24,000.
• Units introduced: 1,000 units.
• Costs added: material ₹3,00,000, conversion ₹2,10,000.
• Completed units: 900 units.
• Closing WIP: 250 units (material 100%, conversion 20% complete).
• Loss: 50 units (difference between total 1,200 and accounted 1,150).

Assumption for abnormal loss: Loss is identified only at final inspection (100% complete on both material and conversion).

Equivalent units and cost per EU (both treatments)

Total costs:

• Material: ₹60,000 + ₹3,00,000 = ₹3,60,000
• Conversion: ₹24,000 + ₹2,10,000 = ₹2,34,000

Exam tip: The point at which loss is identified matters. Here we assume 100% completion at final inspection. If loss occurred earlier, partial conversion costs would apply. Always read the problem for loss point assumptions.

Why separate abnormal loss?

• Normal loss: management accepts it; no corrective action needed.
• Abnormal loss: visible cost item signals inefficiency, defective materials, or poor training. Investigation and corrective action can be targeted.

Key takeaways – Loss Treatment

• Normal loss: EU rows for “process loss” are zero; cost per good unit is higher.
• Abnormal loss: loss units get full EU (material and conversion, depending on point of loss); cost isolated as a P&L charge.
• Total cost remains the same under both treatments – only the allocation differs.
• Abnormal loss treatment provides better cost control information for management.

Exercise 10: Multi-Product, Multi-Process Costing

Intuition: In process costing, when multiple products pass through multiple processes in sequence, each process accumulates costs (transferred‑in, direct materials, conversion) and then allocates them to completed units. The key difference from single‑product costing is that at certain processes units may be split into different products, with some units sold and others transferred forward. This exercise demonstrates how to handle:

• Two products (AX‑100 and AX‑PRO)
• Three work centers (C1, C2, C3)
• Transferred‑in costs from the previous process
• Additional material added at specific points (e.g., packing material for AX‑100)
• Weighted average method for inventory valuation

The flow of units:

No new units start in C2 or C3. All completed units are sold immediately.

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Data

Units

Completion % – Opening WIP

Completion % – Closing WIP

Costs

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Process C1 – First work center

Equivalent units (weighted average)

• Material: all units are 100% complete on material. Equivalent units = (5,300 completed) + (200 closing × 100%) = 5,500
• Conversion: closing WIP is 40% complete. Equivalent units = 5,300 + (200 × 40%) = 5,300 + 80 = 5,380

Cost per equivalent unit

Cost allocation

• Completed & transferred (5,300 units) Material: ₹6 × 5,300 = ₹31,800 Conversion: ₹3 × 5,300 = ₹15,900 Total transferred‑out cost = ₹47,700 (₹9 per unit)

• Closing WIP (200 units) Material: ₹6 × 200 = ₹1,200 Conversion: ₹3 × (200 × 40%) = ₹3 × 80 = ₹240 Total WIP = ₹1,440

Reconciliation: opening WIP (₹3,000 + ₹450) + costs added (₹30,000 + ₹15,690) = ₹49,140 Allocated: ₹47,700 + ₹1,440 = ₹49,140 ✔

Exam tip: The transferred‑out cost from C1 becomes the transferred‑in cost for C2. Always compute it accurately because it flows forward.

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Process C2 – Second work center (split point)

Units

• Opening WIP: 300 (50% conversion)
• Transferred in from C1: 5,300
• Total units to account for: 5,600
• No closing WIP → all 5,600 are completed in C2.

Splitting the completed units

• 60% → AX‑100 (sold immediately): 5,600 × 60% = 3,360 units
• 40% → transferred to C3: 5,600 × 40% = 2,240 units

Equivalent units (no closing WIP) All three cost elements = 5,600 EU each (transferred‑in, conversion, and material – but note: no new material cost here except packing for AX‑100).

Cost per equivalent unit

Cost of units before splitting = ₹9 + ₹2 = ₹11 per unit

AX‑100 (3,360 units) – additional packing material ₹10 per unit

• Transfer cost from C2: 3,360 × ₹11 = ₹36,960
• Packing material: 3,360 × ₹10 = ₹33,600
• Total cost of AX‑100 = ₹70,560 → ₹21 per unit (₹11 + ₹10)

Transferred to C3 (2,240 units)

• No packing material.
• Cost = 2,240 × ₹11 = ₹24,640

Exam tip: In multi‑product processes, watch for costs that apply to only one product (here packing material). They are assigned only to that product’s units.

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Process C3 – Third work center (AX‑PRO)

Units

• Opening WIP: 0
• Transferred in from C2: 2,240
• Total: 2,240
• Closing WIP: 500 (100% material, 70% conversion)
• Completed AX‑PRO: 2,240 – 500 = 1,740 units

Equivalent units

Cost per equivalent unit

Cost per complete AX‑PRO unit = ₹11 + ₹5 + ₹2 = ₹18

Cost allocation

• Completed AX‑PRO (1,740 units): 1,740 × ₹18 = ₹31,320
• Closing WIP (500 units) Transferred‑in: ₹11 × 500 = ₹5,500 Material: ₹5 × 500 = ₹2,500 Conversion: ₹2 × 350 = ₹700 Total closing WIP = ₹8,700

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Summary of costs

Reconciliation of total costs incurred

Opening WIP total = ₹3,000 + ₹450 (C1) + ₹300 + ₹2,700 (C2) = ₹6,450 Costs added during month = ₹30,000 + ₹15,690 (C1) + ₹10,900 + ₹33,600 (C2) + ₹11,200 + ₹4,180 (C3) + transferred‑in flows (already included in added costs of subsequent processes) – but careful: total cash outflow = sum of all original added costs excluding internal transfers = ₹30,000+15,690+10,900+33,600+11,200+4,180 = ₹1,05,570 Add opening WIP ₹6,450 → ₹1,12,020 ✔

Key takeaways

• Multiple processes require sequential cost accumulation: transferred‑in cost from the prior process becomes a cost element in the next.
• Splitting units at a work center (here C2) creates two cost streams: one for a finished product (AX‑100) and one that continues processing (AX‑PRO).
• Weighted average method blends opening WIP costs with current period costs to compute a single cost per equivalent unit for each element.
• Watch for product‑specific costs (e.g., packing material for AX‑100) – they are added only to the units that incur them and increase the unit cost of that product.
• Closing WIP in any process is valued according to its stage of completion for each cost element.

Exercise 11: Stepwise Allocation of Service Department Costs

Cost allocation becomes tricky when service departments support each other. The stepwise allocation method (also called step-down method) recognises inter-departmental services by allocating service department costs one at a time, stopping once each service department's costs have been fully distributed.

The Setup: Mass Electronic Producers

• Production departments: Assembly, Testing
• Service departments: Maintenance, Administration
  • Maintenance spends: 60% Assembly, 35% Testing, 5% Administration
  • Administration spends: 70% Assembly, 20% Testing, 10% Maintenance
• Departmental costs (quarterly):

• Product details:

• Allocation bases: Assembly cost → machine hours; Testing cost → number of units.

Stepwise Allocation — Maintenance First, Then Administration

Step 1: Allocate Maintenance (₹600,000)

Step 2: Allocate Administration (now ₹288,000 + ₹30,000 = ₹318,000)

Only to Assembly and Testing (ignore the 10% back to Maintenance – that would create a further loop). The allocation ratio for these two departments is 70:20 out of 90% (the combined share used).

• Assembly: $\frac{70\%}{90\%} \times 318,000 = 247,333$
• Testing: $\frac{20\%}{90\%} \times 318,000 = 70,667$

Exam tip: In stepwise allocation, once a service department is fully allocated, it no longer receives costs from later steps. This is a shortcut – the full reciprocal method would loop infinitely until the residual is negligible.

Step 3: Total production department costs after allocation

Step 4: Allocate to products

• Assembly uses machine hours: Cost per machine hour $= \frac{7,807,333}{3,120} = 2,502.35$ (approx.)

• Testing uses number of units: Cost per unit $= \frac{1,030,667}{560} = 1,840.48$

Step 5: Total production overhead per product and per unit

Stepwise Allocation — Administration First, Then Maintenance

Step 1: Allocate Administration (₹288,000) to Assembly (70%), Testing (20%), and Maintenance (10%).

• Assembly: $0.70 \times 288,000 = 201,600$
• Testing: $0.20 \times 288,000 = 57,600$
• Maintenance: $0.10 \times 288,000 = 28,800$

Step 2: Allocate Maintenance (now ₹600,000 + ₹28,800 = ₹628,800) to Assembly and Testing (60% + 35% = 95% of its work). Ignore the 5% to Administration (already closed).

• Assembly: $\frac{60\%}{95\%} \times 628,800 = 397,137$
• Testing: $\frac{35\%}{95\%} \times 628,800 = 231,663$

Step 3: Total production department costs

Step 4 & 5: Allocation to products – same procedure yields a slightly different per‑unit overhead (differences < 1%, due to rounding and the order effect). The principle is that the order of allocation matters little when differences are small.

Exam tip: When multiple service departments exist, a common rule is to allocate the smallest service department first. Here, Administration (₹288,000) is smaller than Maintenance (₹600,000). This minimises the error from stopping after one step.

Key Takeaways (Exercise 11)

• Stepwise allocation partially recognises inter‑service‑department usage, unlike direct allocation (which ignores them entirely).
• The allocation order matters; allocate the smallest service department first for better accuracy.
• Once a service department is closed, it no longer receives costs from later steps.
• Final production overhead per product can be computed by using appropriate bases (machine hours for assembly, units for testing).
• The difference between the two orders is usually negligible if the percentages are stable.

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Exercise 12: The Effect of Product Mix on Cost Allocation

When a company adds a new product line (especially customised items), traditional volume‑based allocation can distort costs. This is called cross‑subsidisation: standard products bear costs that are actually caused by customised ones.

The Scenario: Phonics Enterprise

• Original (standard only): 200,000 units/year, indirect costs ₹9,000,000.
• After adding customised orders: total units 300,000; indirect costs ₹18,000,000 (doubled).
• The accountant continues using units produced as the only allocation base.

Cost per unit under old method: $\frac{9,000,000}{200,000} = \text{Rs. }45 \text{ per unit}$

Cost per unit under new method: $\frac{18,000,000}{300,000} = \text{Rs. }60 \text{ per unit}$

Standard products appear to increase in cost by 33% (₹45 → ₹60), even though nothing about their production has changed. The extra ₹90 lakhs of indirect cost is caused by the 100,000 customised units, yet it is spread over all 300,000 units.

Impact on Decision Making

Suppose a customer orders 1,000 standard units with direct cost ₹200 per unit. Under the old rate (₹45 overhead), total cost = ₹245; with 20% markup, price = ₹294. Under the new rate (₹60 overhead), total cost = ₹260; price = ₹312. The customer faces an ₹18 increase for the same product – this could lead to lost sales or unfair pricing.

Cross‑subsidisation: Standard products subsidise customised products. Customised items appear cheaper than they should, while standard items appear more expensive.

Exam tip: This distortion is a classic argument for Activity‑Based Costing (ABC). ABC traces overhead costs to activities and then to products based on their actual consumption of activities, avoiding arbitrary volume‑based allocations.

Key Takeaways (Exercise 12)

• Adding a product line with different cost drivers (e.g., customisation) can distort costs if a single volume‑based base is used.
• Cross‑subsidisation makes low‑volume/complex products seem cheaper and high‑volume/simple products seem more expensive.
• The distortion can lead to poor pricing, product mix, and investment decisions.
• Moving to ABC corrects these distortions by using multiple cost drivers.

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Exercise 13: Choosing the Right Allocation Base

Different departments have different cost structures. Using one allocation base (e.g., machine hours) for all departments can misrepresent costs. A better approach is to match the allocation base to the nature of the department (machine‑intensive vs. labour‑intensive).

The Scenario: Dolphin Leather

• Leather Processing Division: machine‑intensive (2,000 machine hours, 600 labour hours; cost ₹20,00,000 per month).
• Leather Products Division: labour‑intensive (8,000 machine hours, 12,000 labour hours; cost ₹8,00,000 per month).
• Traditionally, the company used a single machine hour rate for both departments.

A special order of 1,000 units requires:

Method A: Machine‑Hour Rate for Both Departments

• Leather Processing rate: $\frac{20,00,000}{2,000} = \text{Rs. }1,000$ per machine hour
• Leather Products rate: $\frac{8,00,000}{8,000} = \text{Rs. }100$ per machine hour

Method B: Machine Hours for Processing, Labour Hours for Products

• Leather Processing rate: same ₹1,000 per machine hour
• Leather Products rate (labour hours): $\frac{8,00,000}{12,000} = \text{Rs. }66.67$ per labour hour

Which Method Is Better?

• Method A overcosts the order by ₹23,333 (3,93,333 – 3,70,000) because it uses machine hours for a labour‑intensive department.
• Method B is more appropriate because it matches allocation bases to cost drivers:
  • Machine hours for the machine‑intensive leather processing division.
  • Labour hours for the labour‑intensive leather products division.

Exam tip: Even after choosing a better base, a single allocation base per department still lumps many costs together (power, depreciation, supervision). Activity‑Based Costing goes further by splitting departmental costs into multiple activities (e.g., setups, inspections, material handling) with separate cost drivers. This is the ultimate refinement.

Key Takeaways (Exercise 13)

• A single volume‑based allocation (e.g., machine hours) across all departments can misstate costs when departments have different cost structures.
• Match the allocation base to the dominant cost driver of each department: machine hours for capital‑intensive, labour hours for labour‑intensive.
• The difference between a naive and a refined allocation can be significant (here ₹23,333).
• Even with improved bases, ABC provides a more accurate picture by breaking costs into activities.

Allocation Bases in Different Industries (Exercise 14)

The choice of an allocation basis depends on the cost object, the nature of the activity, and the principle that costs should be assigned to revenue-generating activities. A single arbitrary basis rarely works; the best basis reflects the underlying driver of consumption.

Guiding principle

Allocate costs to revenue-generating activities, not to support functions or users who do not directly generate revenue. Then choose a base that matches how each activity consumes the resource.

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Situation 1: Business School Library Costs

A school spends ₹20 lakhs on e‑journals and e‑resources used by students, faculty, staff, and visitors. The school runs five programs (the revenue generators). Faculty and visitors pay no fee – they are not revenue sources.

Allocation base – if program durations are uniform, use number of students per program. If durations differ (e.g., 6‑month vs. 12‑month program), use student‑days.

Example

• Program A: 30 students × 6 months (≈180 days) = 5,400 student‑days
• Program B: 100 students × 12 months (≈250 days) = 25,000 student‑days

Total = 30,400 student‑days → each program’s share = its student‑days ÷ total.

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Situation 2: Restaurant with Four Service Types

A restaurant has four segments:

1. Self‑service (customer takes food, minimal effort)
2. Non‑AC hall (waiter takes order, serves, cleans)
3. AC hall (same activities + better ambience)
4. Take‑away / parcel (similar to self‑service but with extra packing)

The restaurant employs 100 workers (non‑cooks). Cook costs are excluded because all segments use the same cooks.

Approach (increasing accuracy)

• Cleaning not needed for take‑away or self‑service.
• Order‑taking not needed for self‑service.

Exam tip: An activity‑based approach is more accurate but requires data collection. Many firms use revenue (an ad‑hoc base) because it is readily available – but it may distort costs.

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Situation 3: District Court

Cost unit: Each case (job) heard by the court. Cost pool: Salaries of judges & employees, rent, electricity, water, maintenance – ₹1,80,000 per day.

Allocation base: Hours (or minutes) the court spends on each case.

Worked example

• Court operations per day: 6 hours of hearings, 20 cases.
• Cost per minute = ₹1,80,000 ÷ (6 hr × 60 min) = ₹500 per minute.
• Case 1: 5 minutes → cost = 5 × ₹500 = ₹2,500.
• Case 2: 1 hour (60 min) → cost = 60 × ₹500 = ₹30,000.

Why this matters – court fees should reflect the cost of time consumed. A small claim (₹5,000) may require 3 hours; a large claim (₹20 lakhs) may require 30 hours → fee ratio should be 10:1 to cover costs.

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Situation 4: Metro Rail (and Indian Railways)

Operation: 30 km network, 20 trains, 12 stations. Costs: salaries, electricity, repairs, depreciation for coaches, rail network, buildings.

Cost unit → Passenger‑kilometer (number of passengers × distance travelled). This captures both the number of users and how far each travels.

Allocation – simplest: total monthly cost ÷ total passenger‑kilometers = cost per passenger‑km.

Telescoping costing – for systems with fixed and variable costs:

Result: Long‑distance passengers pay a lower cost per km than short‑distance passengers because fixed costs are spread over more km. This is called telescoping costing.

Extension – Indian Railways With multiple train types (passenger, super‑fast, express), passenger‑km remains a suitable base. Different trains may have different cost structures; separate cost pools can be set up per train type.

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Summary Table

Key takeaways

• Allocation bases must match how costs are consumed by the cost object.
• Always ask: Is the cost driver a volume measure (units, hours), an activity measure, or a simple count?
• Activity‑based allocation yields better accuracy when different cost objects use activities in different proportions.
• Revenue is a convenient but often misleading allocation base – it can hide inefficiencies.
• Telescoping costing is the natural result of allocating fixed costs by number of users and variable costs by usage (e.g., passenger‑km).
• The choice of allocation basis can significantly affect pricing decisions (court fees, ticket prices).

Exercise 16: Techbyte – HR Overhead Allocation

Techbyte is a large IT company with 40,000 software engineers across five verticals (Banking & Insurance 14,000, Retail 8,000, Telecom 4,000, Healthcare 6,000, Transport 8,000). The HR department has 162 staff performing 10 activities. Total HR department cost includes annual employee cost (sum of salaries of 162 staff) and other department costs ₹322 lakh (electricity, depreciation, etc.).

Part A: Traditional Overhead Rate

Current practice: All HR costs are pooled and allocated based on software engineer days (each engineer works 200 days per year).

• Annual employee cost = ₹6,23,67,000
• Other department cost = ₹3,22,00,000
• Total HR cost = ₹6,23,67,000 + ₹3,22,00,000 = ₹9,45,67,000
• Total software engineer days = 40,000 employees × 200 days = 80,00,000 days

$\text{HR overhead rate} = \frac{9,45,67,000}{80,00,000} \approx \text{Rs. }11.82 \text{ per software engineer day}$

Exam tip: Traditional overhead rate = total indirect cost ÷ total allocation base. Here the base is total employee days (not hours). Always check the given base.

Part B: Activity-Based Costing (ABC)

Step 1 – Allocate other department costs (₹322 lakh) to activities Use number of staff per activity as allocation basis.

$\text{Cost per staff} = \frac{322,00,000}{162} \approx \text{Rs. }198,765$

Step 2 – Compute total activity cost = annual employee cost + allocated other costs Step 3 – Compute activity driver rates (cost per unit of activity output)

Recruitment costs ₹1,334 per hire; contract employment ₹1,932 per employee; visa processing ₹726 per case; performance assessment ₹948 per employee; labour-law compliance ₹47,147 per compliance; health and safety ₹204 per employee; and training ₹529 per day. The worked project total implies a payroll allocation of ₹50,071, or about ₹166.90 per employee.

Part C: Project Cost Comparison (Traditional vs ABC)

Project: 300 software engineers, 220 days.

• 80 stationed in UK (need visa)
• 40 short travel (need visa)
• 60 new campus hires (need recruitment)
• All 300 need performance assessment, payroll, health & safety

Traditional method: Using the unrounded overhead rate:

$\text{Cost} \approx 300 \times 220 \times 11.820875 = \text{Rs. }7,80,178$

ABC method:

• Recruitment: 60 × ₹1,334 = ₹80,040
• Visa & travel: (80+40) × ₹726 = ₹87,120
• Performance assessment: 300 × ₹948 = ₹2,84,400
• Payroll: implied project allocation = ₹50,071
• Health & safety: 300 × ₹204 = ₹61,200
• Total for activities supported by the project data = ₹5,62,831

Training, legal-compliance, dispute-handling, and community-service costs require additional project-driver assumptions. They should be added only when those driver quantities are specified.

Comparison:

Key takeaways

• Traditional overhead rate masks differences in HR resource consumption across projects.
• ABC traces costs to activities (recruitment, visa, training) → more accurate project costing.
• The choice of allocation base (number of staff per activity) for indirect costs can significantly impact activity costs.
• When using ABC, some activities may not apply to a project (e.g., contract employment, community events).

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Exercise 17: Decolam Corporation – Product Costing

Decolam manufactures three wooden-flooring products: Prime Shield, Sponge Soft, and Glazed Supreme. Traditional costing groups material and production labour as machine-shop direct cost, then applies overhead at 30% of that direct cost. ABC uses five activities. The company targets a 20% profit margin on selling price, equivalent to a 25% markup on total cost.

Given Data

ABC activity drivers and rates:

Traditional Costing

Activity-Based Costing

Comparison of Prices (Traditional vs ABC)

Distortion: Traditional costing undercharges Prime Shield and overcharges Glazed Supreme because one overhead rate does not reflect their different activity use. ABC assigns setup, machining, finishing, quality-control, and material-handling costs through their relevant drivers.

Revised Pricing using Activity‑Based Profit Markup

Current total profit under traditional (20% margin = 25% markup on total cost): $\text{Total profit} = 25\% \times (\text{sum of all total costs})$ Sum of total costs (traditional) = ₹1,50,80,000 + ₹60,50,261 + ₹2,24,90,000 = ₹4,36,20,261 Profit = 0.25 × ₹4,36,20,261 = ₹1,09,05,065

Under ABC, total activity cost (sum of activity costs across products) = ₹88,80,000 + ₹26,70,000 + ₹68,70,000 = ₹1,84,20,000 Required profit markup on activity cost only to earn same profit: $\text{Markup} = \frac{1,09,05,065}{1,84,20,000} \approx 59.20\%$

Revised price per unit (₹/sq ft) = (material cost + activity cost + 59.02% × activity cost) ÷ quantity

Impact of revised pricing:

• Standard product (Prime Shield) price increases (94.25 → 115.69) – it was previously under-costed.
• Premium product (Glazed Supreme) price decreases (234.27 → 196.14) – it becomes more competitive.
• Mid-range product (Sponge Soft) price remains similar (151.26 → 157.01).

Exam tip: Changing the profit margin base from total cost to activity cost can significantly alter product prices. The same absolute profit is distributed differently across products.

Key takeaways

• Traditional costing distorts costs when products consume overhead activities in different proportions.
• ABC traces overhead through the activities each product actually uses.
• When switching from traditional to ABC, high‑complexity products may become cheaper (correctly) and simple high‑volume products more expensive.
• Profit margin can be applied to total cost (traditional) or to activity cost only (ABC‑based margin). The latter aligns pricing with activity consumption.
• A 20% margin on total cost is not the same as a 59% markup on activity cost – the choice affects relative product profitability.

Exercise 18: PCN Magic Show — ABC and Cost-Volume-Profit

PCN is a magician performing ~50 shows/year (attendance 1000–2000). The cost structure is mostly fixed, with only ticketing varying per customer. This exercise applies cost-volume-profit (CVP) analysis and introduces opportunity cost in decision-making.

Cost structure per show

Revenue: ticket price ₹300 per customer.

Net income at different attendance levels

Note: without the stall fee, net income for 1,000 attendees would be a loss of ₹8,000. The fixed fee converts the loss into a small profit.

Operating leverage effect

Fixed costs dominate (₹2,58,000 out of total). When attendance rises from 1,500 to 2,000 (a 33% increase), net income jumps from ₹1,37,000 to ₹2,62,000 — a 91% increase. This disproportionate profit growth is the fixed-cost leverage (high operating leverage).

School event with opportunity cost

A local school (2,000 students) invites PCN to perform. The school bears all costs except three items:

• Setting up stage: ₹30,000
• Material costs: ₹50,000
• Transportation: ₹20,000
• Total direct cost: ₹1,00,000

Minimum charge (naive): ₹1,00,000 (break-even on out-of-pocket costs).

Opportunity cost

If the school event is not held, 10% of students (200 students) plus their parents (3 members each) would attend PCN’s regular public show — i.e., 600 tickets. Those tickets would have contributed:

$\text{Contribution per ticket} = \text{Price} - \text{Ticketing cost} = 300 - 50 = \text{Rs. }250$

Opportunity loss: $600 \times 250 = \text{Rs. }1,50,000$

Total cost including opportunity cost: ₹1,00,000 + ₹1,50,000 = ₹2,50,000

Therefore, PCN should charge at least ₹2,50,000 to break even after accounting for lost regular sales.

Decision when school offers ₹2,00,000

However, the opportunity cost of ₹1,50,000 is uncertain (some attendees may still come to the regular show; some may attend both). The school’s ₹2,00,000 is certain. In practice, a manager might accept a lower offer if the uncertainty is high — this is a gray area in decision-making.

Exam tip: In CVP with opportunity costs, always quantify the contribution margin lost. The decision rule is: accept if incremental revenue ≥ incremental out-of-pocket costs + opportunity cost. But real-world judgment may override strict numbers.

Key takeaways

• Distinguish fixed costs (₹2,58,000) from variable costs (ticketing ₹50/customer).
• High fixed costs → high operating leverage → profits grow faster than revenue.
• Minimum charge for a special order must cover direct costs + any opportunity cost from lost regular sales.
• Contribution per regular ticket = price – variable cost.
• Uncertainty in opportunity cost can justify accepting a lower price if the alternative is risky.

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Exercise 15: Product Variety and Cost Structure

Compare two factories in the same city:

• Factory A: Manufactures few items (e.g., Apple phones, Bosch washing machines) — single-product or few-product.
• Factory B: Manufactures a large variety (e.g., Samsung phones, LG washing machines) — multi-product.

Key differences and cost implications

Why cost per unit rises with product variety

When a firm moves from a single product to customized/multi-product, indirect costs increase sharply. Example from earlier module: indirect cost per unit rose from ₹45 to ₹60 after introducing customization. This is because:

• More design changes
• More setups
• More quality inspections
• More material handling
• More scheduling and supervision

These costs are not captured well by traditional volume-based costing — hence the need for activity-based costing (ABC) to trace them to products.

Exam tip: Product variety increases indirect costs disproportionately. ABC reveals that high-variety products are often under-costed by traditional systems and may be less profitable than they appear.

Key takeaways

• Multi-product firms are more complex → higher design, manufacturing, inventory, and support costs.
• Complexity drives up indirect costs, raising total cost per unit.
• Traditional costing masks the true cost of variety; ABC is needed.
• Moving from few products to many products increases indirect cost (example: ₹45 → ₹60).