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Microlesson · 5-min read

Process Costing - Definition, Industry Features, Steps, Methods, Inter-Process Profits, and Operation Costing

## Process Costing

### Definition

A method of costing where material passes through two or more processes before becoming a finished product. Costs are accumulated per process per period.

### Industries Where Process Costing Applies

Look for these features:

1. Factory divided into distinct processes/cost centres (each = a stage of production)

2. Manufacturing is continuous — processes run sequentially, selectively, or simultaneously

3. Output of one process = Input of the next

4. End products are identical / homogeneous units

5. Lot identity cannot be traced (e.g., sugar from sugarcane — impossible to link a bag of sugar to a specific cane lot)

6. Production may yield joint products and/or by-products

Examples: Sugar, chemicals, cement, textiles, petroleum refining, pharmaceuticals

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### Five Steps in Process Costing

StepAction
1Analyse physical flow of units: opening WIP + fresh inputs → completed + closing WIP + losses
2Calculate equivalent units for each cost element (materials, labour, overheads separately)
3Determine total cost for each cost element for the period
4Compute cost per equivalent unit = Total cost ÷ Equivalent units
5Assign costs: to completed units, units transferred, closing WIP, abnormal loss/gain

#### Equivalent Units — Critical Concept

WIP is partially complete. Convert to equivalent completed units:

  • Materials (often added at start): WIP units × % material added (often 100%)
  • Labour & Overheads: WIP units × % of completion

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### Two Methods for WIP Valuation

MethodApproachUse When
FIFOOpening WIP costs kept separate; current period costs applied only to current workCosts change significantly between periods
Weighted AverageOpening WIP costs + current period costs pooled; average rate computedSimpler; costs are relatively stable

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### Inter-Process Profits

When goods transfer between processes above cost (at market value or cost + profit %):

  • Each process acts as a profit centre
  • Enables comparison: process output cost vs. market price at that completion stage
Detail
AdvantageFacilitates performance evaluation; incentivises efficiency per process
DisadvantageCreates unrealised profits (stock not yet sold shows profit in accounts); adds complexity

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### Operation Costing (Hybrid System)

  • Used when a company produces multiple product variants with different materials but similar conversion activities
  • Also called: Hybrid product costing system
Cost TypeTreatment
Material costsTracked separately per variant (job-order / batch / unit basis)
Conversion costs (labour + OH)Accumulated by department/process; applied via predetermined rate

Example: A shoe manufacturer makes Deluxe (leather) and Regular (synthetic) models. Same cutting/stitching process → pool conversion costs. Different materials → track separately.

Industries: Ready-made garments, shoes, jewellery, any multi-variant manufacturer with shared conversion.

Worked example

### Example 1

Equivalent Units Calculation: Process 1 introduces 1,000 units. 800 units completed and transferred. Closing WIP = 200 units (100% complete for materials, 60% complete for labour/overheads).

  • Equivalent units – Materials = 800 + (200 × 100%) = 1,000
  • Equivalent units – Labour = 800 + (200 × 60%) = 920
  • Equivalent units – Overheads = 800 + (200 × 60%) = 920

If total material cost = ₹10,000 → Cost per equivalent unit (material) = ₹10

If total labour cost = ₹9,200 → Cost per equivalent unit (labour) = ₹10

Cost of closing WIP: Materials = 200 × ₹10 = ₹2,000; Labour = 120 × ₹10 = ₹1,200

### Example 2

Inter-Process Profit: Process 1 produces 500 units at a cost of ₹50,000 (₹100/unit). Transfer price to Process 2 = ₹120/unit (market value). Transfer value = ₹60,000. Inter-process profit = ₹10,000. This ₹10,000 profit is unrealised until the final product is sold — a provision for unrealised profit must be made in financial statements so external reporting is not overstated.

### Example 3

Operation Costing: Garment factory makes two variants — Deluxe (silk fabric) and Regular (cotton fabric). Monthly conversion costs = ₹1,00,000 for 10,000 garments total. Predetermined conversion rate = ₹10 per garment (regardless of variant). Material cost: Deluxe silk = ₹500/garment; Regular cotton = ₹150/garment. Total cost per garment: Deluxe = ₹510; Regular = ₹160.

⚠️ Common exam mistakes

  • Using the same equivalent unit percentage for materials and conversion costs — materials added at the start of a process are 100% complete even in WIP, while conversion costs reflect actual % of completion.
  • Under FIFO, mixing opening WIP costs with current period costs — FIFO keeps them separate; only the Weighted Average method pools them.
  • Treating inter-process profit as realised profit — it is unrealised until the final product reaches an external customer; omitting the unrealised profit provision overstates financial results.
  • Confusing Operation Costing with Job Costing or Process Costing — it is a hybrid: material tracked per variant (like job), conversion pooled per department (like process).
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