Inventory Accounting and Valuation

Module 5 Overview

Inventory – raw materials, work in progress, and finished goods – sits at the heart of the income statement after revenue. The cost of raw materials flows through production stages and eventually becomes cost of goods manufactured, which is subtracted from revenue to yield gross profit. Proper inventory accounting and valuation is essential for accurate profit measurement.

Components of inventory

Cost flow through inventory

Expenses attach to raw materials, then flow sequentially into work in progress and finished goods. The total cost of goods completed during the period is the cost of goods manufactured.

Connection to gross profit

The income statement sequence:

1. Revenue (covered in Module 4).
2. Cost of goods manufactured – the accumulated cost of finished units.
3. Gross profit = Revenue – Cost of goods manufactured.

Key point: Inventory valuation directly affects the size of gross profit. Overstating inventory inflates cost of goods manufactured and understates gross profit (or vice versa).

Key takeaways

• Inventory comprises raw materials, work in progress, and finished goods.
• Costs flow from raw materials → work in progress → finished goods.
• Cost of goods manufactured = the cost of all units completed in the period.
• Gross profit = Revenue – Cost of goods manufactured.
• Accurate inventory valuation is critical for reliable profit reporting.

Periodic and Perpetual Inventory Valuation

For trading firms (buy-and-sell, no value addition), the core accounting challenge is variation in purchase price. The same product is bought at different prices over time. When a sale occurs, which cost should be matched with the revenue? Two broad approaches exist.

Periodic Inventory Valuation

Process: Physically count unsold units at the end of the accounting period, assign a value (the inventory value), then compute cost of sales as:

$$\text{Cost of sales} = \text{Total purchases} - \text{Ending inventory value}$$

Worked example – TV dealer

• Purchases (3 lots):
  • 30 units @ ₹10,000 → ₹300,000
  • 40 units @ ₹9,000 → ₹360,000
  • 30 units @ ₹11,000 → ₹330,000
• Total purchases = ₹990,000
• Sales: 80 units @ ₹14,000 → ₹1,120,000
• Physical count at end: unsold units assigned a value of ₹220,000 (inventory value)

$$\begin{aligned} \text{Cost of sales} &= 990,000 - 220,000 = 770,000 \\ \text{Profit} &= 1,120,000 - 770,000 = 350,000 \end{aligned}$$

Suitability: Works well when the firm deals in few items and the closing unsold quantity is small.

Perpetual Inventory Valuation

Process: Every purchase and every issue (sale/transfer) is recorded immediately. The inventory records are updated continuously – no need to wait for a physical count.

Worked example – Auto component (constant unit price)

Assume all purchases are at ₹200/unit.

• Total purchases: 500+600+800 = 1,900 units → ₹380,000
• Total issues: 400+500+900 = 1,800 units → ₹360,000
• Closing balance: 100 units → ₹20,000

When price is constant, the same result could be obtained by periodic counting of 100 units. But for a manufacturer with 500+ different components, physical counting every month is infeasible. Perpetual inventory provides the closing value at any time from the records alone – a requirement for bank reporting and internal control.

Exam tip: The key advantage of perpetual over periodic is real-time knowledge of inventory value without physical counting. This becomes critical when purchase prices vary significantly.

Key takeaways – Periodic vs. Perpetual

• Periodic relies on a year-end physical count; cost of sales = total purchases minus ending inventory.
• Perpetual updates inventory after every transaction; no physical count needed for valuation.
• Periodic suitable for small, simple trading firms; perpetual necessary for large, diverse inventories.
• When purchase prices are constant, both methods yield the same profit. The difference matters when prices vary.
• Perpetual is the standard for manufacturers and large retailers.

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Inventory Accounting Methods – Overview

Now relax the assumption of constant purchase price. The following six months of transactions illustrate the problem:

Note: Calculate the balance quantity at any point by netting purchases and issues.

The challenge: When units are issued, decide which purchase rate(s) to assign to the issued units and ending inventory. Common cost-flow assumptions are FIFO, LIFO, and weighted average.

Key takeaways – Setup for costing methods

• With varying purchase prices, the cost of sales and ending inventory depend on the cost flow assumption used.
• Apply the three methods to the raw transactions to compute issue and balance values.
• Cost flow assumption ≠ physical flow of goods; it is an accounting rule for assigning costs.

Specific Identification Method

Specific identification tracks the exact cost of each individual unit in inventory. Instead of averaging or assuming a flow of costs, it directly matches the physical unit’s purchase price to its valuation. This is the most accurate method — but only practical when units are few, unique, and easily traced.

Intuitively: if you have a barcode on every item that records its purchase price, you just scan the items still in stock and sum their costs. The result is closing inventory at the exact historical cost of those specific units.

Calculation formula

[ \text{Closing inventory} = \sum_{\text{each unit}}\text{purchase price of that unit} ]

Once closing inventory is known, material consumption (cost of goods issued to production) is:

[ \text{Material consumption} = \text{Total purchases} - \text{Closing inventory} ]

(Assuming no opening inventory or that opening inventory is included in total purchases.)

Worked example

Total purchases for the period = ₹8,40,000

[ \text{Material consumption} = 8,40,000 - 69,000 = 7,71,000 ]

When to use specific identification

• Number of closing units is small.
• Technology exists to identify each unit’s cost (e.g., barcode, RFID).
• Items are high‑value, differentiable, and rarely interchangeable.

Exam tip: Specific identification is the only method that uses actual costs rather than an assumption (FIFO, LIFO, weighted average). It provides the most precise inventory valuation but is rarely used for large volumes of identical items.

Key takeaways

• Each unit is valued at its own purchase price – no flow assumption.
• Closing inventory = sum of individual unit costs.
• Material consumption = total purchases − closing inventory.
• Suitable when units are few, identifiable, and tracked (e.g., via barcodes).
• Accurate but labour-intensive; impractical for mass‑produced goods.

First-In-First-Out Method (FIFO)

First-In-First-Out (FIFO) assumes that the goods purchased earliest are the first to be used or sold. In a physical store, this works if each purchase batch is stored in separate, labelled boxes; the storekeeper issues from the oldest box first. Where physical separation is impossible (e.g., stacked goods, chemicals in a tank), the accounting assumption still applies: the cost of the earliest purchase is assigned to the first issue, regardless of actual physical flow.

$\text{Cost of goods sold (COGS)} = \text{cost of oldest inventory layers first}$

$\text{Ending inventory} = \text{cost of most recent purchases}$

Perpetual Inventory under FIFO

In a perpetual system, every purchase and issue updates the inventory record immediately. The storekeeper always knows:

• Purchase value – total cost of all units bought so far.
• Issue value (COGS) – total cost of units issued so far.
• Closing stock value – cost of units remaining (= purchase value − issue value).

Worked example: Complete FIFO calculation

Transactions (all in a single financial year):

Each issue is allocated to the oldest available layers. The table below shows how the inventory layers evolve after every transaction.

Detailed issue calculations:

1. Jan 15 – Issue 400 units From Jan 1 purchase (500 @ 200). Issue: 400 × 200 = ₹80,000. Remaining layer: 100 @ 200.

2. Feb 15 – Issue 500 units

   • 100 units from remaining Jan 1 layer @ 200 → ₹20,000.
   • 400 units from Feb 1 purchase (400 @ 230) → ₹92,000. Total issue: 500 units, ₹1,12,000. Remaining layers: (none from Jan), (none from Feb).

3. Mar 15 – Issue 900 units

The stated March allocation uses 200 units at ₹230 and 700 units at ₹210. This conflicts with the earlier stated exhaustion of the February layer. Treat the following figures as an illustration of the stated issue-cost calculations, not as a fully reconcilable perpetual-inventory schedule.

Stated issue-cost calculations:

• Jan 15: 400 units @ 200 → ₹80,000.
• Feb 15: 100 @ 200 + 400 @ 230 → ₹20,000 + ₹92,000 = ₹1,12,000.
• Mar 15: 200 @ 230 + 700 @ 210 → ₹46,000 + ₹1,47,000 = ₹1,93,000.
• Apr 15: 100 @ 210 + 700 @ 180 → ₹21,000 + ₹1,26,000 = ₹1,47,000.
• May 15: 300 @ 180 + 200 @ 220 → ₹54,000 + ₹44,000 = ₹98,000.
• Jun 15: 500 @ 220 + 100 @ 250 → ₹1,10,000 + ₹25,000 = ₹1,35,000.

Total issue value = 80,000 + 112,000 + 193,000 + 147,000 + 98,000 + 135,000 = 765,000. ✓

The listed purchases total ₹794,000, while the worked closing-stock calculation uses a stated purchase total of ₹840,000 and issue total of ₹765,000, giving ₹75,000. Because these totals conflict, do not use this example to validate a ledger; use it to practise the stated FIFO issue allocations.

Exam tip: In a perpetual FIFO system, the issue value (COGS) is determined by the cost of the oldest layer at the time of issue. Always track layers sequentially.

First-In-First-Out Method (FIFO)

FIFO assumes that the goods purchased earliest are the first to be used or sold. Physically, this works if each purchase batch is stored separately (e.g., labelled boxes); the storekeeper issues from the oldest box first. Where physical separation is impractical (stacked items, liquid chemicals), the accounting assumption still applies: the cost of the oldest purchase is assigned to the first issue, irrespective of actual physical flow.

$$\text{COGS} = \text{cost of the oldest inventory layers first}$$ $$\text{Ending inventory} = \text{cost of the most recent purchases}$$

The FIFO logic for each issue

When a new issue occurs, the accountant takes units from the oldest available layer until the issue quantity is filled:

Worked example: FIFO in a perpetual inventory

The following transactions occurred during the year. All purchase costs are per unit.

Issue allocations

Each issue is split into parts, each part taken from a different purchase layer (oldest first).

Totals:

• Total purchases value: ₹8,40,000
• Total issue value (COGS): ₹7,65,000
• Closing stock value: ₹75,000 (remaining 300 units @ ₹250)

Closing stock equals ₹8,40,000 – ₹7,65,000 = ₹75,000.

Advantage of perpetual inventory

With a perpetual FIFO system, the storekeeper can provide the inventory value, total purchase value, and total consumption value at any time – all updated continuously with each transaction.

Key takeaways

• FIFO assumes the oldest purchase costs flow out first into COGS.
• Each issue is allocated in layers, starting from the earliest purchase still in stock.
• In a perpetual system, inventory records are updated after every purchase and issue.
• Closing stock value = total purchase value − total issue value (COGS).
• The example illustrates the split‑layer technique: when an issue exceeds a layer’s remaining units, the remainder is taken from the next oldest layer.

Last-In-First-Out (LIFO) Method

Last-in, first-out (LIFO) assumes that the most recently purchased goods are the first to be issued or sold. The oldest inventory remains in stock, often carrying historical costs that can be far below current replacement cost. While LIFO can create multiple inventory layers and complex record‑keeping, it is required by U.S. GAAP for tax purposes under certain conditions and is widely used by U.S. companies. Most other countries prohibit LIFO under IFRS.

How LIFO works: a complete example

Use the same transactions as in the FIFO and weighted‑average illustrations. All figures in Indian rupees (₹).

Transaction history

Step‑by‑step application of LIFO

January 15 issue (400 units) Only one lot exists (Jan 1 lot at ₹200). Apply that rate:

• Issue cost: 400 × ₹200 = ₹80,000
• Remaining: 100 units @ ₹200 = ₹20,000

February 15 issue (500 units) Latest purchase is Feb 1 at ₹230. Issue from that lot:

• Issue cost: 500 × ₹230 = ₹115,000
• Remaining stock: 100 units (Jan @ ₹200) + 100 units (Feb @ ₹230) = 200 units, value = 100×200 + 100×230 = ₹43,000

March 15 issue (900 units) Latest purchase is Mar 1 at ₹210. Issue 800 units from Mar lot, then 100 units from the next latest (Feb @ ₹230).

• Issue cost: 800×₹210 + 100×₹230 = ₹168,000 + ₹23,000 = ₹191,000
• Remaining stock: 100 units (Jan @ ₹200) = ₹20,000

April 15 issue (800 units) Latest purchase is Apr 1 at ₹180. Issue from that lot:

• Issue cost: 800×₹180 = ₹144,000
• Remaining stock: 100 units (Jan @ ₹200) + 200 units (Apr @ ₹180) = 300 units, value = 100×200 + 200×180 = ₹20,000 + ₹36,000 = ₹56,000

May 15 issue (500 units) Latest purchase is May 1 at ₹220. Issue from that lot:

• Issue cost: 500×₹220 = ₹110,000
• Remaining stock: 100 units (Jan @ ₹200) + 200 units (Apr @ ₹180) + 200 units (May @ ₹220) = 500 units, value = 100×200 + 200×180 + 200×220 = ₹20,000 + ₹36,000 + ₹44,000 = ₹100,000

June 15 issue (600 units) Latest purchase is Jun 1 at ₹250. Issue 400 units from Jun lot, then 200 units from May lot (the next latest):

• Issue cost: 400×₹250 + 200×₹220 = ₹100,000 + ₹44,000 = ₹144,000
• Remaining stock: 100 units (Jan @ ₹200) + 200 units (Apr @ ₹180) = 300 units, value = 100×200 + 200×180 = ₹20,000 + ₹36,000 = ₹56,000

Summary of LIFO results

Total consumption (cost of goods sold) = sum of all issue costs: ₹80,000 + ₹115,000 + ₹191,000 + ₹144,000 + ₹110,000 + ₹144,000 = ₹784,000

Ending inventory (June 30) = 300 units valued at ₹56,000

The ending inventory consists entirely of the oldest layers (Jan 1 and Apr 1 lots). Even though the latest purchase price was ₹250, the inventory carries costs as low as ₹180 and ₹200 — a clear mismatch with current market value.

Why LIFO is used (and why it’s controversial)

• U.S. tax advantage: In periods of rising prices, LIFO yields higher cost of goods sold, lower taxable income, and therefore lower taxes. The U.S. Internal Revenue Code permits LIFO; most other accounting standards (IFRS) prohibit it.
• Income smoothing: LIFO matches current costs against current revenues, reducing the impact of price fluctuations on reported profit.
• Chaos in record‑keeping: As the example shows, LIFO creates multiple inventory layers that must be tracked separately. When a later purchase is issued before an earlier one, the older layers may stay on the books indefinitely, leading to inventory layers at very different unit costs.

Exam tip: LIFO is tested primarily through its effect on the income statement and balance sheet. Memorise that during inflation, LIFO → higher COGS → lower net income → lower taxes. During deflation, the opposite occurs.

Key takeaways

• LIFO assumes the latest goods purchased are the first sold/issued.
• Ending inventory under LIFO consists of the oldest costs (often far below current replacement cost).
• In the worked example, LIFO gave a total consumption of ₹784,000 and closing stock of ₹56,000.
• LIFO is allowed in the U.S. but prohibited under IFRS; if permitted, it can reduce taxable income during inflation.
• Tracking multiple cost layers makes LIFO administratively complex compared to FIFO or weighted average.

Conservatism and Net Realizable Value (Lower of Cost or Market)

The conservatism principle dictates that when market value of inventory drops below cost, the accountant must use market value instead of cost. If market value is unavailable, net realizable value (NRV) is used as the ceiling.

NRV = estimated selling price minus estimated completion and selling costs.

For work‑in‑progress (WIP) inventory, NRV is determined by working backwards from the finished goods selling price.

Worked example – WIP write‑down

Given:

• Cost of WIP in books = ₹20,000
• Estimated completion cost = ₹10,000
• Selling price of finished goods = ₹28,000

$\text{NRV} = 28{,}000 - 10{,}000 = \text{Rs. }18{,}000$

Since cost (₹20,000) > NRV (₹18,000), inventory is written down to ₹18,000.

Key takeaways

• Apply lower of cost or market (LCM) when market value falls below cost.
• For WIP, use NRV (selling price minus costs to complete and sell).
• Write‑down reduces inventory value and increases cost of goods sold (conservatism).

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Weighted Average Method

The weighted average method smooths price fluctuations by recalculating the average cost per unit after each purchase. This average is then used to value all subsequent issues until the next purchase.

Calculation logic

Whenever a purchase is received, update the average rate:

$\text{New average rate} = \frac{\text{(Quantity in stock} \times \text{old rate}) + (\text{new purchase quantity} \times \text{purchase rate})}{\text{Total units in stock after purchase}}$

Issues are valued at the current average rate.

Worked example – six months of transactions

*Calculations: 1 Feb avg: (100×200 + 600×230) / 700 = (20,000 + 138,000)/700 = 158,000/700 = 225.714 1 Mar avg: (200×225.71 + 800×210) / 1,000 = (45,142 + 168,000)/1,000 = 213,142/1,000 = 213.14 1 Apr avg: (100×213.14 + 1,000×180) / 1,100 = (21,314 + 180,000)/1,100 = 201,314/1,100 = 183.01 1 May avg: (300×183.01 + 700×220) / 1,000 = (54,903 + 154,000)/1,000 = 208.90 1 Jun avg: (500×208.90 + 400×250) / 900 = (104,450 + 100,000)/900 = 227.17

Material consumption value (sum of all issues) = ₹7,71,849.

Comparison of Inventory Methods

Exam tip: In an inflationary period, FIFO → higher profits (lower COGS); LIFO → lower profits (higher COGS). Weighted average sits between the two.

Regulatory & practical notes

• LIFO is not allowed in many countries (e.g., India) but is permitted in the U.S.
• Once a method is chosen, consistency requires it be followed in subsequent years.
• Tax authorities accept any of the four methods.
• Computationally, weighted average is easy in computerised systems; FIFO and LIFO require tracking multiple layers.
• LIFO’s long‑run problem: closing stock may carry prices from many past periods. To simplify, accountants using LIFO periodically average the inventory cost and treat that as the latest purchase, erasing old layers.

Key takeaways for weighted average

• Recalculate average cost after each purchase; issue at that average.
• Smoothes price ups and downs – consumption value lies between FIFO and LIFO.
• Preferred by many Indian companies for its moderate tax effect.
• Closes with a single average rate per unit, avoiding multiple layers.

Retail Method

The retail method of inventory valuation is used by retail stores (e.g., Big Bazaar) that carry hundreds or thousands of line items. For such firms, tracking every unit’s exact cost is impractical—even a physical count is too costly. Instead, they estimate closing inventory by working backwards from sales, using the store’s average gross margin percentage.

Intuition: If we know total sales and the typical markup on goods, we can back out the cost of what was sold. Then everything not sold must be the remaining stock.

How it works

1. Compute cost of sales (the cost of goods actually sold during the period): $\text{Cost of Sales} = \text{Sales} - (\text{Gross Margin \%} \times \text{Sales})$ This rearranges the standard profit equation: Sales – Cost of Sales = Gross Profit.

2. Compute closing inventory: $\text{Closing Inventory} = \text{Opening Stock} + \text{Purchases} - \text{Cost of Sales}$

Key assumption: The gross margin percentage must be uniform across all items in the store. If different product categories earn different margins, the method must be applied separately to each category using its own margin.

Worked example

A retail store has:

• Opening stock: ₹20 lakh
• Purchases during the period: ₹300 lakh
• Sales: ₹280 lakh
• Average gross margin: 5%

Step 1 – Cost of Sales

$\text{Cost of Sales} = 280 - (0.05 \times 280) = 280 - 14 = \text{\text{Rs. }266 lakh}$

Step 2 – Closing Inventory

$\text{Closing Inventory} = 20 + 300 - 266 = \text{\text{Rs. }54 lakh}$

When the retail method is (and isn’t) used

Exam tip: If a problem gives different gross margin percentages for different categories, do not use a single average. Compute cost of sales separately for each category, then sum them before finding closing inventory.

Why barcode scanning changes things

Most modern retail stores scan barcodes at checkout. The accounting system can then capture the actual cost of each item sold (from purchase records). In that setting, the retail method—which only provides an approximate cost of sales—is no longer needed; the system can report exact closing inventory.

Key takeaways

• Retail method estimates closing stock using Sales × (1 – Gross Margin %) to find cost of sales.
• Formula: Closing Inventory = Opening Stock + Purchases – Cost of Sales.
• Requires uniform gross margin percentage across items (or use category-level margins).
• Provides an approximation; accurate when physical counting or barcode tracking is infeasible.
• Modern barcode systems can make the retail method obsolete by giving exact cost per unit sold.

Inventory Accounting for Manufacturing Companies

Manufacturing firms hold three distinct inventory layers — raw material, work in progress (WIP), and finished goods — unlike trading firms that only hold finished goods for resale. Costs flow sequentially through these accounts as materials are transformed into sellable products.

The key challenge: correctly allocate costs between completed units (transferred to finished goods) and partially finished units (remaining in WIP), while also deciding how to treat period costs (indirect manufacturing expenses like rent or supervisor salaries).

Cost Components and Allocation Logic

Allocation of direct expenses between completed and WIP units is based on estimates (e.g., the percentage attributable to each group). In this illustration, period costs are not allocated to WIP and are assigned only to finished goods.

Worked Example: Garment Manufacturer

Given data:

• 1 Jan 2024: Purchased raw material worth ₹3,00,000 (cash).
• 5 Jan 2024: Issued ₹2,00,000 raw material to production for 1,000 shirts.
• Production incurs ₹1,00,000 direct expenses (for processing 1,000 units).
• After processing: 800 units completed and transferred to finished goods warehouse; 200 units remain incomplete in WIP.
• Estimate: 10% of direct expenses attributable to WIP (200 units), 90% to completed units.
• Additional period cost: ₹60,000 (charged entirely to finished goods, not WIP).
• 600 of the 800 finished units are sold for ₹3,00,000.

Step 1: Raw Material Account

Step 2: Work in Progress Account

WIP receives raw material and direct expenses; value is split between completed units and incomplete units.

WIP charges:

• Raw material from stores: ₹2,00,000 (for 1,000 units)
• Direct expenses incurred: ₹1,00,000

Allocation to completed units (800 units):

• Material cost for 800 units: $\text{Rs. }2,00,000 \times \frac{800}{1000} = \text{Rs. }1,60,000$
• Direct expenses (90%): $\text{Rs. }1,00,000 \times 0.90 = \text{Rs. }90,000$
• Cost of goods manufactured (transferred to finished goods): $\text{Rs. }1,60,000 + \text{Rs. }90,000 = \text{Rs. }2,50,000$

Allocation to WIP (200 units):

• Material cost for 200 units: $\text{Rs. }2,00,000 \times \frac{200}{1000} = \text{Rs. }40,000$
• Direct expenses (10%): $\text{Rs. }1,00,000 \times 0.10 = \text{Rs. }10,000$
• WIP closing balance: $\text{Rs. }40,000 + \text{Rs. }10,000 = \text{Rs. }50,000$

WIP Account:

Step 3: Finished Goods Account

Period costs of ₹60,000 are added directly to finished goods (not through WIP).

Finished goods charges:

• Transfer from WIP (cost of goods manufactured): ₹2,50,000
• Period cost added: ₹60,000
• Total cost for 800 units: $\text{Rs. }2,50,000 + \text{Rs. }60,000 = \text{Rs. }3,10,000$

Cost per unit: $\frac{\text{Rs. }3,10,000}{800} = \text{Rs. }387.50$

Cost of sales (600 units sold): $\text{Rs. }3,10,000 \times \frac{600}{800} = \text{Rs. }2,32,500$

Closing finished goods (200 units): $\text{Rs. }3,10,000 - \text{Rs. }2,32,500 = \text{Rs. }77,500$

Finished Goods Account:

Step 4: Profit and Loss (Sales and Cost of Sales)

Step 5: Inventory Valuation (Balance Sheet)

Step 6: Cost Reconciliation

Total cash spent during period:

• Raw material purchase: ₹3,00,000
• Direct expenses: ₹1,00,000
• Period costs: ₹60,000 Total spending: ₹4,60,000

Split:

• Cost of sales: ₹2,32,500
• Total inventory: ₹2,27,500 Sum: ₹4,60,000 ✅

Cost Flow Diagram

Key Decisions in Practice

• Periodic vs. perpetual inventory: if raw material types are few, prices stable, and quantities small, periodic may suffice. Otherwise perpetual preferred.
• Cost flow assumption: FIFO, LIFO, weighted average, or specific identification (when closing items are few and costs traceable).
• Transport and other procurement costs are added to raw material cost per unit; if untraceable to individual items, they are pooled and allocated by material quantity or value.
• Indirect manufacturing expenses (factory rent, supervisor salary, repairs, insurance, quality control, depreciation) are either allocated to finished goods as overhead or treated as period costs charged directly. This illustration uses the latter policy.

Exam tip: Period costs are never allocated to work in progress — they are either added to finished goods or expensed immediately. This distinction is frequently tested.

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Key Takeaways

• Manufacturing inventory has three layers: raw material → WIP → finished goods. Costs flow sequentially.
• Direct expenses (labour, electricity) are allocated between completed and incomplete units based on estimates (e.g., percentage of work done).
• Period costs (indirect manufacturing expenses) are charged directly to finished goods, not to WIP.
• The cost of goods manufactured is the transfer value from WIP to finished goods; it includes material, direct expenses, and (if policy) a share of overhead.
• Total costs incurred (purchases + direct expenses + period costs) must equal cost of sales + ending inventory — use this reconciliation to verify accuracy.
• Gross profit = Sales − Cost of sales; closing inventory appears on the balance sheet.

Inventory Accounting in Service Industries

Service industries (consulting, legal, construction) differ from manufacturing in their inventory composition. While manufacturing has raw material, work in progress (WIP), and finished goods, service firms hold only work in progress — and some hold none at all.

Why only work in progress?

Service companies execute jobs for clients. A job starts when a client signs a contract and ends when the job is delivered. During the job, all costs incurred — primarily employee costs and other direct expenses — are accumulated in a job cost sheet. The job cost sheet is opened at the start of the project and closed once the project is completed and handed over. The balance of all open (uncompleted) job cost sheets at the end of an accounting period equals the company’s work in progress inventory.

Exam tip: A service firm’s “work in progress” is not physical — it is the accumulated cost on uncompleted projects. Pure service firms (e.g., Amazon Retail, BlueDot, LIC, Air India) have no work in progress at all because they deliver services instantly and do not accumulate costs over multiple periods.

The job cost sheet process

All open job cost sheets sum to WIP on the balance sheet.

Pure service firms — no inventory

Some service companies — Amazon Retail, BlueDot, LIC, Air India — have no formal “job” that spans multiple periods. Their services are consumed immediately (e.g., flight seat, insurance coverage, cloud service). For these firms, all costs are expensed as incurred; there is no work in progress. Inventory is effectively zero.

The distinction between job-cost service firms and pure service firms affects whether any asset (WIP) appears on the balance sheet. This topic is extended in management accounting (future course).

Key takeaways

• Service industries have no raw material or finished goods; only work in progress is possible.
• Job cost sheets track all costs of a client project until completion; open sheets = WIP.
• Pure service firms (no multi-period jobs) have zero inventory.
• Employee costs and direct expenses are the primary components of service WIP.

Inventory Valuation: FIFO Method (Perpetual System)

FIFO (first-in, first-out) assumes the oldest inventory is issued first. Intuitively: goods are sold in the order they were bought – like a queue. This matters because purchase prices change over time, so the cost of goods sold (COGS) reflects older, often cheaper prices, while ending inventory reflects the most recent purchase prices.

How FIFO works in a perpetual system

Every time a purchase occurs, a new “layer” of inventory with its own unit cost is added. When an issue (sale) occurs, the system consumes the oldest layers first, splitting the issue quantity across multiple layers if necessary. The cost of goods sold is the sum of the costs of those consumed layers.

Worked example: 6-month data (FIFO)

Data: purchases (first of month) and issues (15th of month) in units and ₹/unit.

Step-by-step FIFO calculation (showing layers)

Jan 1 – Opening balance: Layer L1: 500 units @ ₹200 = ₹1,00,000.

Jan 15 – Issue 400 units. FIFO: take from L1. Issue value = 400 × 200 = ₹80,000. Remaining L1: 100 units @ ₹200 = ₹20,000.

Feb 1 – Purchase: New layer L2: 600 units @ ₹230 = ₹1,38,000. Inventory: L1 (100 @ ₹200) + L2 (600 @ ₹230) → 700 units, value ₹1,58,000.

Feb 15 – Issue 500 units. FIFO: take all of L1 (100 @ ₹200) + 400 from L2 @ ₹230. Issue value = (100×200) + (400×230) = ₹20,000 + ₹92,000 = ₹1,12,000. Remaining L2: 200 units @ ₹230 = ₹46,000.

Mar 1 – Purchase: New layer L3: 800 @ ₹210 = ₹1,68,000. Inventory: L2 (200 @ ₹230) + L3 (800 @ ₹210) → 1,000 units, value ₹2,14,000.

Mar 15 – Issue 900 units. FIFO: take all of L2 (200 @ ₹230) + 700 from L3 @ ₹210. Issue value = (200×230) + (700×210) = ₹46,000 + ₹1,47,000 = ₹1,93,000. Remaining L3: 100 units @ ₹210 = ₹21,000.

Apr 1 – Purchase: New layer L4: 1000 @ ₹180 = ₹1,80,000. Inventory: L3 (100 @ ₹210) + L4 (1000 @ ₹180) → 1,100 units, value ₹2,01,000.

Apr 15 – Issue 800 units. FIFO: take all of L3 (100 @ ₹210) + 700 from L4 @ ₹180. Issue value = (100×210) + (700×180) = ₹21,000 + ₹1,26,000 = ₹1,47,000. Remaining L4: 300 units @ ₹180 = ₹54,000.

May 1 – Purchase: New layer L5: 700 @ ₹220 = ₹1,54,000. Inventory: L4 (300 @ ₹180) + L5 (700 @ ₹220) → 1,000 units, value ₹2,08,000.

May 15 – Issue 500 units. FIFO: take all of L4 (300 @ ₹180) + 200 from L5 @ ₹220. Issue value = (300×180) + (200×220) = ₹54,000 + ₹44,000 = ₹98,000. Remaining L5: 500 units @ ₹220 = ₹1,10,000.

Jun 1 – Purchase: New layer L6: 400 @ ₹250 = ₹1,00,000. Inventory: L5 (500 @ ₹220) + L6 (400 @ ₹250) → 900 units, value ₹2,10,000.

Jun 15 – Issue 600 units. FIFO: take all of L5 (500 @ ₹220) + 100 from L6 @ ₹250. Issue value = (500×220) + (100×250) = ₹1,10,000 + ₹25,000 = ₹1,35,000. Remaining L6: 300 units @ ₹250 = ₹75,000.

Final summary

Closing inventory value is consistent with the cost of the most recent layer (300 from June purchase @ ₹250). Also note: ₹8,40,000 – ₹7,65,000 = ₹75,000 ✓.

Exam tip: In FIFO perpetual, when an issue exceeds the oldest layer, split the quantity across layers. The cost of the oldest layer is fully used before moving to the next. This splitting is the most error-prone step – always check the balance of each layer before and after.

What makes FIFO different from LIFO

LIFO (last-in, first-out) uses the same perpetual structure but issues from the most recent purchase layer first. The calculations are analogous but use the latest cost layers.

Key takeaways

• FIFO issues inventory in the order it was purchased – oldest cost first.
• In a perpetual system, each purchase creates a layer tracked by unit cost.
• When issuing, always consume the oldest available layer; if insufficient, take from next layer and split the quantity.
• COGS reflects older, lower costs in a rising price environment → higher profit (but higher tax).
• Ending inventory is valued at the most recent purchase costs – a closer approximation to current replacement cost.
• The sum of all issue values under FIFO equals total purchases minus closing inventory value (a cross-check).

LIFO (Last-In, First-Out) Method

LIFO (Last-In, First-Out) assumes that the most recently purchased units are issued first. Intuitively, the cost of goods sold (COGS) reflects the newest costs, while ending inventory consists of the oldest layers. Under rising prices, LIFO yields higher COGS and lower ending inventory than FIFO.

Worked Example (Same Transactions Used for LIFO)

Data:

Total purchases value: ₹8,40,000.

LIFO Allocation (Step-by-Step)

• Jan 15 issue (400 units): Only one layer (Jan 1 at ₹200). Issue value = $400 \times 200 = \text{Rs. }80,000$. Closing stock: 100 units @ ₹20,000.
• Feb 15 issue (500 units): Latest layer is Feb 1 (600 @ ₹230). Issue all 500 from Feb purchase. Value = $500 \times 230 = \text{Rs. }1,15,000$. Remaining: 100 units Jan @ ₹200 + 100 units Feb @ ₹230 → 200 units, value ₹43,000.
• Mar 15 issue (900 units): Issue 800 from Mar 1 purchase (800 @ ₹210 = ₹1,68,000) + 100 from Feb balance (100 @ ₹230 = ₹23,000). Total issue value = ₹1,91,000. Remaining: 100 units Jan @ ₹200 (₹20,000).
• Apr 15 issue (800 units): Issue 800 from Apr 1 purchase (800 @ ₹180 = ₹1,44,000). Remaining: 200 units Apr @ ₹180 + 100 units Jan @ ₹200 → 300 units, value ₹56,000.
• May 15 issue (500 units): Issue 500 from May 1 purchase (500 @ ₹220 = ₹1,10,000). Remaining: 200 units May @ ₹220 + 200 units Apr @ ₹180 + 100 units Jan @ ₹200 → 500 units, value ₹1,00,000.
• Jun 15 issue (600 units): Issue 400 from Jun 1 purchase (400 @ ₹250 = ₹1,00,000) + 200 from May balance (200 @ ₹220 = ₹44,000). Total issue = ₹1,44,000. Remaining: 200 units Apr @ ₹180 + 100 units Jan @ ₹200 → 300 units, value ₹56,000.

Final LIFO Summary:

• Total issues (COGS): ₹7,84,000
• Ending inventory: ₹56,000 (100 units @ ₹200 + 200 units @ ₹180)

Exam tip: LIFO requires tracking multiple cost layers. In periods of rising prices, LIFO produces a higher COGS and lower ending inventory than FIFO, which reduces reported profit (and income tax) but may lower asset values on the balance sheet.

Key takeaways (LIFO)

• Latest purchases are issued first.
• Layers of older costs remain in inventory.
• Under rising prices: highest COGS, lowest ending inventory.
• Computationally more complex than FIFO or weighted average.

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Weighted Average Cost Method

The weighted average cost method computes a new average cost per unit after every purchase. All subsequent issues are valued at this average rate. The method smooths out price fluctuations and yields COGS and inventory values that lie between FIFO and LIFO.

Average Rate Calculation

After each purchase: $\text{Average rate} = \frac{\text{Total cost of inventory available}}{\text{Total units available}}$

Worked Example (Same Transactions)

Final Weighted Average Summary:

• Total issues (COGS): ₹7,71,849
• Ending inventory: ₹68,151

Exam tip: The weighted average rate changes only after a purchase – issues do not affect the average. This method is simpler to compute than LIFO because only one rate per period is used.

Key takeaways (Weighted Average)

• Average cost recalculated at each purchase.
• All issues valued at the latest average.
• Yields COGS and inventory values between FIFO and LIFO under rising/falling prices.
• Easier to implement than LIFO – no need to track separate layers.

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Comparison of FIFO, LIFO, and Weighted Average

Using the same transaction data, the three methods produce different COGS and ending inventory values:

• Under rising prices (as in this example: rates increase from ₹200 to ₹250), LIFO shows the highest COGS and lowest inventory; FIFO shows the opposite; weighted average falls in between.
• The moderate effect of weighted average is one reason many accountants prefer it – it avoids extreme swings in profit and asset values.
• Weighted average also simplifies record‑keeping because it does not require tracking individual cost layers.

Exam tip: In periods of rising prices, LIFO gives the lowest net income (higher COGS) and lowest ending inventory. This can reduce income tax but may violate the natural flow of goods in many industries. FIFO gives the highest net income and highest inventory. Weighted average provides a compromise.

Key takeaways (Comparison)

• All three methods use the same total purchase cost (₹8,40,000) – only the allocation to COGS and inventory differs.
• LIFO = most recent costs to COGS; FIFO = oldest costs to COGS; Weighted Average = blended cost.
• In rising price environments: LIFO > Weighted Average > FIFO in COGS (reverse for inventory).

Inventory Valuation Methods (FIFO, LIFO, Weighted Average)

Inventory cost flow assumptions determine how the cost of goods sold (COGS) and ending inventory are valued when prices change. The choice directly impacts net income, taxes, and reported assets.

Why it matters: In rising prices (inflation), different methods produce different profits and inventory balances even when physical quantities are identical.

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Periodic vs. Perpetual Inventory Systems

The same cost flow assumption (FIFO, LIFO, Weighted Average) can be applied under either system, but perpetual requires tracking individual layers.

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The Three Cost Flow Assumptions

FIFO (First-In, First-Out)

• Oldest units are sold first.
• During rising prices → lower COGS, higher profit, higher ending inventory.
• Intuition: physically plausible for perishable goods.

LIFO (Last-In, First-Out)

• Newest units are sold first.
• During rising prices → higher COGS, lower profit, lower ending inventory.
• Intuition: matches current costs with current revenue (economic matching).
• More complex under perpetual: requires splitting quantities across layers when a purchase layer is only partly used.

Weighted Average

• A single average cost per unit is computed after each purchase (perpetual) or for the whole period (periodic).
• During rising prices → COGS and ending inventory lie between FIFO and LIFO.
• Intuition: smooths price fluctuations; no need to track individual layers.

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Worked Example 1: Periodic Inventory with Constant Prices (Ajanta Electrical)

Data (January 2023):

• Opening inventory: 3,000 units @ ₹600
• Purchases: 15,000 units @ ₹620
• Sales: 14,000 units @ ₹720
• Ending inventory: 4,000 units

All prices are constant throughout the month. Sales revenue is the same under all methods:

$\text{Sales} = 14\,000 \times 720 = \text{Rs. }1,00,80,000$

Cost of Sales & Profit by Method

Weighted average unit cost: $\frac{3\,000\times600 + 15\,000\times620}{18\,000} = \frac{18\,00\,000 + 93\,00\,000}{18\,000} = 616.\overline{6}$

Exam tip: In rising prices (cost per unit increases from ₹600 to ₹620), FIFO yields the highest profit and LIFO the lowest. Weighted average moderates the impact.

Key takeaways

• Under periodic inventory, COGS = total goods available minus ending inventory, using the selected cost flow.
• Constant selling price means profit differences come solely from COGS.
• The ranking of profits (FIFO > WA > LIFO) is a classic exam result under inflation.

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Worked Example 2: Perpetual Inventory with Changing Prices (Cutfast Engineering)

This example demonstrates perpetual inventory – the cost of each issue is based on the most recent cost flow assumption, updated after every transaction.

Transactions (summarised):

Total purchases: 10,300 units, total issues: 10,100 units → ending inventory 200 units.

FIFO (Perpetual)

• Issues use the oldest available cost layers. When a layer is exhausted, the next oldest is used.
• Example (day 10, issue 800): 100 units from the ₹120 layer, then 700 from the ₹130 layer.
• Final consumption (COGS) = ₹12,82,000. Ending inventory = ₹28,000 (200 units at mixed rates, essentially from oldest remaining layers).

LIFO (Perpetual)

• Issues use the most recent purchase layer first. If insufficient, go to earlier layers.
• Example (day 31, issue 1,800): 1,500 from the latest ₹140 layer, then 100 from the ₹125 layer, then 200 from the ₹130 layer – requiring a three-way split.
• Final consumption = ₹12,85,000. Ending inventory = ₹25,000 (from earliest layers: 100 units @ ₹130 + 100 @ ₹120).

Exam tip: LIFO perpetual involves tracking many small layers – a common source of arithmetic errors on exams.

Weighted Average (Perpetual)

• After each purchase, a new average cost is computed.
• All issues between purchases use that average rate. No splitting needed.

Example of average update: After day 8 purchase: Quantity = 100 + 2,500 = 2,600; Value = ₹12,000 + ₹3,25,000 = ₹3,37,000; Average rate = ₹3,37,000 / 2,600 = ₹129.62

• Final consumption = ₹12,82,761. Ending inventory = ₹27,239.

Comparison of Results

• Again, FIFO gives the lowest COGS (highest profit), LIFO the highest COGS (lowest profit), and Weighted Average lies in between.
• The differences are smaller than in Example 1 because prices both rose and fell during the month, but the overall trend was upward (from ₹120 to ₹140).

Key takeaways

• Perpetual FIFO and LIFO require splitting issues into multiple cost layers when the available quantity in the current layer is insufficient.
• Weighted average is simpler computationally: only one average rate is maintained.
• The ranking of COGS (LIFO > WA > FIFO) holds under rising prices, but can reverse if prices are falling.

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How the Methods Connect: Cost Flow and Profit

Key takeaways

• FIFO – yields highest net income and highest ending inventory during inflation.
• LIFO – yields lowest net income and lowest ending inventory during inflation; more record-keeping.
• Weighted Average – simple, avoids extreme values; COGS and inventory fall between FIFO and LIFO.
• The same physical inventory can produce very different financial statements depending on the method chosen.

Impact on Profit and Cash Flow Under Different Inventory Methods (Problem: Digital World)

Inventory accounting affects cost of sales and closing stock, which in turn changes profit and therefore tax outflow. However, pre‑tax cash flow is unaffected because the total cash paid for purchases is the same regardless of the method used.

The scenario

• Company: Digital World (dealer of HP laptops)
• Purchases:
  • 1,200 units @ ₹60,000 per unit
  • 1,800 units @ ₹70,000 per unit
  • Total units purchased: 3,000
• Sales: 2,500 units @ ₹80,000 per unit (all cash)
• Tax rate: 30%

Profit after tax under FIFO, LIFO, Weighted Average

Key observation: In an inflationary environment (prices rising from ₹60,000 to ₹70,000),

• FIFO yields the highest profit (older, cheaper costs matched to revenue).
• LIFO yields the lowest profit (newer, higher costs matched to revenue).
• Weighted average falls in between.

Pre‑tax and post‑tax cash flow (all cash transactions)

• Cash from customers = Sales = ₹200,000,000 (same for all)
• Cash paid to suppliers = Total purchases = 1,200×60,000 + 1,800×70,000 = ₹198,000,000 (same for all)
• Pre‑tax cash flow = ₹200,000,000 – ₹198,000,000 = ₹2,000,000 (identical under all methods)

Exam tip: Pre‑tax cash flow is not affected by the choice of inventory method because total cash outflows for purchases do not change. Only the cost allocation (when goods are sold) differs.

• Tax paid = from the profit calculation above
• Post‑tax cash flow = Pre‑tax cash flow (–) Tax paid

LIFO minimises tax → highest (least negative) post‑tax cash flow. This is the cash flow advantage of LIFO when prices rise.

Even if purchases are partly on credit, the relative ranking (LIFO → best post‑tax cash flow, FIFO → worst) holds.

Key takeaways

• Inventory method changes profit and tax, but not pre‑tax cash flow when all purchases/sales are cash.
• In inflation: FIFO → highest profit, LIFO → lowest profit, weighted average in between.
• LIFO reduces tax outflow → improves post‑tax cash flow.
• Pre‑tax cash flow (₹2,000,000) is identical across methods; post‑tax cash flow differs because of tax on reported profit.

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Cost Flow Through Inventory Stages (Problem: NaturePro)

Inventory valuation does not stop at cost of goods sold – costs flow through raw materials, work in progress (WIP), and finished goods before reaching the profit & loss account.

The scenario

NaturePro produces organic chemicals. Opening balances (₹’000s):

• Material inventory: 200
• Work in progress: 60
• Finished goods: 140

Transactions during the period (₹’000s):

1. Purchased material: 800
2. Transport charges: 80 (added to material cost)
3. Production drew material: 900
4. Salaries & wages: 300
5. Other manufacturing expenses: 300
6. Transferred finished goods to warehouse: 1,400
7. Sold goods (cost 1,200) for revenue: 1,800
8. Selling & administrative expenses: 100
9. Tax rate: 30%

Inventory movement (T‑account style)

• Total closing inventory = 180 + 160 + 340 = 680
• Cost of goods sold = 1,200

Profit & loss account

Visual flow of costs

Key takeaways

• All manufacturing costs (material, labour, overhead) flow into WIP and are transferred to finished goods when complete.
• Only the cost of goods sold (from finished goods) hits the profit & loss account.
• Closing inventory values (material, WIP, finished goods) are calculated by tracking movements in each account.
• The cost flow method (FIFO/LIFO/WA) affects the allocation of costs to COGS and closing stock, but the physical flow of costs through stages is independent of the accounting method.

Inventory Accounting and Valuation

Inventory valuation directly affects reported profit: if inventory is undervalued, profit is understated; if overvalued, profit is overstated. The goal is to assign a cost to closing inventory that faithfully reflects the cost of goods available for sale.

$\text{Cost of Goods Manufactured} = \text{Total Manufacturing Expenses} - \text{Closing Inventory}$

Periodic vs. Perpetual Systems

• Periodic: simple but less timely; requires a physical stocktake.
• Perpetual: provides real‑time inventory value; requires more record‑keeping.

Exam tip: In a perpetual system, you can compute cost of goods sold (COGS) at any moment without waiting for a physical count.

Cost Flow Assumptions

When items are purchased at different prices, a cost flow assumption is needed to assign costs to issues and ending inventory. Three common methods:

• FIFO and LIFO require careful tracking of receipts and issues.
• Weighted average simplifies record‑keeping and is the most common choice today.
• Specific identification is used only when the number of units and items is small.

Retail Method (for Retail Businesses)

Used to approximate the cost of sales without tracking every item’s cost.

$\text{Cost of Sales} = \text{Total Sales Value} - \text{Average Gross Margin}$

• First compute the average gross margin from past periods.
• Deduct this from total sales to estimate cost of sales.

Inventory in Different Sectors

• Manufacturing companies maintain three inventory accounts:

  • Raw materials (stores)
  • Work in progress (WIP) (shop floor)
  • Finished goods (warehouse)

• Value is tracked through stages: as materials move from stores to shop floor to finished goods, cost is accumulated at each stage (value addition).

• Service firms use job cost sheets for each client job. All expenses for the job are booked on the sheet.

• Closing work in progress for a service firm equals the sum of all incomplete job cost sheets.

Accounting Fraud and Audit

Many accounting frauds involve incorrect inventory valuation (e.g., overstating inventory to inflate profit). Auditors give special attention to inventory accounting and valuation before certifying financial statements.

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Key Takeaways

• Inventory valuation directly impacts reported profit; understatement → lower profit, overstatement → higher profit.
• Periodic vs. perpetual systems differ in timing and effort.
• FIFO, LIFO, weighted average, and specific identification are alternative cost flow assumptions.
• Weighted average avoids tracking layers and is widely used.
• Retail method estimates cost of sales using average gross margin.
• Manufacturing tracks raw materials, WIP, and finished goods; service firms use job cost sheets.
• Inventory misvaluation is a common source of accounting fraud; auditors scrutinize it heavily.