Process costing

Commerce (General / Accounting and Finance / Banking and Insurance) (B.Com) · Cost and management accounting · free study notes for exams, placements and interviews

In short

Process costing is the method used where a product passes through a series of continuous, repetitive processes and output is homogeneous, so cost is collected process-wise for a period and averaged over output instead of being traced to individual jobs. It answers two questions: what did each process cost per unit, and how is cost split between finished output, losses and part-finished work. It is standard practice in sugar, cement, fertiliser, petroleum refining, chemicals, paints, pharmaceuticals, steel, paper, textiles and FMCG plants - exactly the industries covered by cost records and cost audit in India. In B.Com examinations it is a high-weight numerical chapter (process accounts, abnormal loss/gain, equivalent production, joint products), and in placement rounds for costing, plant-finance and MIS roles it is tested through process account preparation and per-unit cost reasoning.

Explained

What process costing is and when it applies

Definition: a costing method in which costs are accumulated for each process or department for an accounting period and the average cost per unit is found by dividing net process cost by output units.
Features: continuous production, standardised homogeneous output, output of one process becomes the input (raw material) of the next, unavoidable losses, and work-in-progress at period end.
Cost unit is physical and natural: tonne of cement, litre of paint, kg of sugar, metre of cloth, KL of petroleum product.
Costs are direct to the process (process materials, process labour, direct expenses) plus apportioned overheads; what is "indirect" in job costing is often direct to a process here (e.g. a dedicated supervisor).
A separate Process Account is opened for each process; the last process transfers its output to the Finished Stock Account (Finished Stock A/c debited, process account credited).
Related variants: single or output costing (one product, one process - bricks, mines), operation costing (process costing applied to each operation), and operating/service costing (a different method, for services).

Basis	Job/batch costing	Process costing
Cost unit	Job, batch, contract	Process output unit
Output	Heterogeneous, to order	Homogeneous, continuous
Cost collection	Per job on a job card	Per process for a period
Cost per unit	Actual, job-specific	Average of the period
WIP	Incomplete jobs	Equivalent production needed
Losses	Usually not normal/routine	Normal and abnormal loss accounted
Transfer	Job completed and delivered	Output transferred process to process

Process accounts and the cost build-up

Debit side of a process account: units and cost of input, materials added, direct wages, direct expenses, apportioned overheads, and abnormal gain.
Credit side: normal loss (at scrap/realisable value only), abnormal loss (at normal cost per unit), output transferred to the next process, and by-product realisation.
Both sides are kept in quantity and value, so the account self-balances on units as well as rupees - a useful exam check.
Inter-process transfer at cost is the simple case. Many firms transfer at cost plus a percentage (transfer price) to judge whether a process is competitive against buying out that intermediate.
With transfer pricing, closing stock held in the next process contains unrealised inter-process profit, which must be eliminated to value stock at cost in the financial accounts (three-column format: cost, profit, total).
Overheads are absorbed process-wise on a logical base - machine hours in a capital-intensive process, labour hours or wages in a labour-intensive one.

Normal loss, abnormal loss and abnormal gain

Normal loss: the unavoidable loss inherent in the process (evaporation, shrinkage, chemical reaction, handling) expressed as a percentage of input. Its cost is absorbed by good units; only its scrap/realisable value is credited to the process.
Hence cost per unit = (total cost − scrap value of normal loss) ÷ (input units − normal loss units). Normal loss units are never charged with cost.
Abnormal loss: actual loss in excess of normal (machine breakdown, bad quality input, operator error). Valued at the normal cost per good unit, credited to the process and debited to Abnormal Loss A/c; its own scrap realisation is credited there, and the net loss goes to the Costing Profit and Loss Account.
Abnormal gain (abnormal effectives): actual output exceeds expected output, so loss was less than normal. Valued at the same normal cost per unit, debited to the process account and credited to Abnormal Gain A/c; that account is debited with the scrap value of the normal loss not realised, and the net gain goes to Costing P&L.
Abnormal gain and abnormal loss cannot both arise in the same process in the same period.
Keeping abnormal items out of the process cost prevents a one-off breakdown from distorting the product cost - the cost-control purpose of the split.
Terminology: waste (no value, may cost money to dispose - disposal cost is added to process cost), scrap (incidental residue with small value), spoilage (units beyond rectification, sold as scrap), defectives (can be rectified - rework cost charged to the process if normal, to Costing P&L if abnormal).

Work-in-progress and equivalent production

Equivalent production (equivalent units, EU) converts part-finished units into the number of fully finished units they represent: EU = physical units × degree of completion, computed element-wise (material, labour, overhead) because material is usually fully issued at the start while conversion is incomplete.
Standard four-statement solution:
1. Statement of equivalent production - units completed plus EU in closing WIP (plus EU of abnormal loss/gain).
2. Statement of cost per equivalent unit - cost of each element ÷ its EU.
3. Statement of evaluation - value completed output, closing WIP and abnormal items.
4. Process account - posted from the above.
Weighted average (average cost) method: opening WIP cost is merged with current cost and spread over all equivalent units (units completed + EU in closing WIP). Opening WIP's own degree of completion is not separately needed. Simple, smooths price changes.
FIFO method: opening WIP is finished first; only current period costs are divided by current period EU = (EU needed to complete opening WIP) + (units started and completed) + (EU in closing WIP). Gives a truer current-period unit cost and better cost control when prices move.
LIFO and standard cost methods exist in texts; standard cost process accounts transfer variances to variance accounts. FIFO and weighted average are what examinations test.
Treatment of losses in equivalent production: normal loss is ignored (no EU, no cost), abnormal loss and abnormal gain are included at their degree of completion - taken as 100% unless the question states the stage of inspection.
Degree of completion must be read carefully: "material 100%, labour and overhead 60%" is the usual pattern; material added in a later process may itself be partly complete.

Joint products and by-products

Split-off point: the stage at which jointly produced outputs become separately identifiable. Costs before it are joint costs and must be apportioned; costs after it are separable (post-separation) costs and are directly traced.
Joint products: two or more main products of comparable commercial value from the same process (petrol, diesel, kerosene from crude; mustard oil and cake).
By-product: incidental output of minor value (molasses and bagasse in sugar, glycerine in soap). Co-product: separate products from a common facility that could be made independently.
Methods of apportioning joint cost: physical units/quantity, sales value at split-off, net realisable value (NRV), constant gross margin (reverse cost) method, average unit cost, survey/weighted factor (points) method, and market value after further processing.
By-product accounting: non-cost methods credit the realisation to the process (reducing joint cost) or to Costing P&L; the cost method apportions a share of joint cost to the by-product.
Decision rule for further processing: process beyond split-off only if incremental revenue > incremental separable cost. Apportioned joint cost is sunk and irrelevant to this decision - a favourite interview trap.

Indian standards, statute and practice

Cost Accounting Standards of the Institute of Cost Accountants of India (ICMAI) govern how elements are measured: CAS-6 material cost, CAS-7 employee cost, CAS-3 production and operation overheads, CAS-22 manufacturing cost, and CAS-19 Joint Costs, which requires joint cost apportionment on a rational, consistently applied basis and by-product realisation to be credited to the process.
Ind AS 2 / AS 2 (Inventories): WIP and finished goods are valued at the lower of cost and net realisable value; cost includes normal production overheads at normal capacity, excludes abnormal losses and idle-capacity cost - this is why abnormal loss goes to P&L and not into stock value.
Companies (Cost Records and Audit) Rules, 2014 (framed under section 148 of the Companies Act, 2013) require prescribed companies - largely regulated and process industries such as sugar, cement, fertiliser, petroleum, drugs, steel, paper, electricity - to maintain cost records in form CRA-1, which is organised by process/product group; applicability thresholds and the industry lists have been amended more than once, so check the current rules before applying them.
GST implications are separate from costing, but stock transfer of intermediates between distinct registered units is a taxable supply and affects the transfer price used.

Advantages and limitations

Advantages: simple averaging, low clerical cost, process-wise cost control and comparison against standards, easy valuation of homogeneous stock, quick per-unit cost for pricing and yield monitoring.
Limitations: average cost hides variation within the period; WIP completion percentages are estimates and open to manipulation; joint cost apportionment is arbitrary, so product-wise profit figures must not be used for marginal decisions; historical nature means errors in one process carry forward; inter-process profit complicates reconciliation with financial accounts.

Key points

Process costing - averaging method for continuous, homogeneous production, cost collected process-wise per period.
Cost per unit - (total process cost − normal loss scrap value) ÷ (input units − normal loss units).
Normal loss - unavoidable; carries no cost, credited only at scrap value; its cost is borne by good units.
Abnormal loss - excess over normal; valued at normal cost per unit; net of scrap it goes to Costing P&L.
Abnormal gain - shortfall of actual loss below normal; debited to process at normal cost, debited with scrap value forgone.
Units check - a process account must balance in quantity as well as in value.
Equivalent production - part-finished units expressed as finished units, computed separately for material and conversion.
Weighted average - opening WIP cost merged with current cost; one rate for all units completed and in closing WIP.
FIFO - current cost only ÷ current EU; opening WIP is completed first and carries its old cost plus completion cost.
Inter-process profit - transfer at cost plus margin to test competitiveness; unrealised profit in closing stock is eliminated.
Split-off point - where joint products become identifiable; before it costs are joint, after it separable.
Joint cost bases - physical units, sales value at split-off, NRV, constant gross margin, survey method.
By-product - minor-value incidental output; its realisation is normally credited to the process cost.
Further processing decision - compare incremental revenue with incremental separable cost; ignore apportioned joint cost.
Yield - actual output ÷ input × 100; a key process-industry KPI monitored against standard yield.
Ind AS 2 / AS 2 - stock at lower of cost and NRV; abnormal loss and idle capacity excluded from inventory cost.
CAS-19 - joint costs apportioned on a rational, consistent basis; CRA-1 cost records for notified process industries.

Formulas and examples

Normal loss units = Input units × normal loss %; Expected (normal) output = Input − Normal loss
Cost per unit = (Total process cost − Scrap value of normal loss) ÷ (Input units − Normal loss units) [₹ per unit]
Abnormal loss units = Expected output − Actual output; Abnormal gain units = Actual output − Expected output
Value of abnormal loss or gain = Units × cost per unit (as above)
Amount to Costing P&L = Abnormal loss cost − its scrap realisation, or Abnormal gain value − scrap value forgone
Equivalent units (per element) = Physical units × degree of completion
Weighted average cost per EU = (Opening WIP cost + Current period cost) ÷ (Units completed + EU in closing WIP)
FIFO cost per EU = Current period cost ÷ [EU to complete opening WIP + units started and completed + EU in closing WIP]
Unrealised profit in closing stock = Closing stock value × (Profit included in transfer price ÷ Total transfer value)
Joint cost to a product = Joint cost × (Sales value or NRV of that product ÷ Total of all products)
NRV = Final sales value − post-separation processing cost − selling and distribution cost
Yield % = (Actual output ÷ Input) × 100

Example 1 - Process account with abnormal loss. Process A: input 1,000 kg of material at ₹50/kg; direct wages ₹12,400; overheads ₹8,000. Normal loss 10% of input, scrap realises ₹20/kg. Actual output transferred to Process B: 850 kg.

Total cost = 50,000 + 12,400 + 8,000 = ₹70,400. Normal loss = 100 kg, scrap value = 100 × 20 = ₹2,000.
Cost per unit = (70,400 − 2,000) ÷ (1,000 − 100) = 68,400 ÷ 900 = ₹76/kg.
Expected output 900 kg, actual 850 kg → abnormal loss 50 kg × 76 = ₹3,800.
Output transferred = 850 × 76 = ₹64,600.
Abnormal Loss A/c: ₹3,800 less scrap 50 × 20 = ₹1,000 → ₹2,800 to Costing P&L.

Process A A/c	Kg	₹		Kg	₹
Material	1,000	50,000	Normal loss	100	2,000
Wages	-	12,400	Abnormal loss	50	3,800
Overheads	-	8,000	To Process B	850	64,600
Total	1,000	70,400	Total	1,000	70,400

Example 2 - Abnormal gain. Input 2,000 units; material ₹80,000; wages ₹32,000; overheads ₹23,000. Normal loss 5% of input, scrap ₹20/unit. Actual output 1,950 units.

Total cost ₹1,35,000; normal loss 100 units, scrap ₹2,000.
Cost per unit = (1,35,000 − 2,000) ÷ 1,900 = 1,33,000 ÷ 1,900 = ₹70.
Expected output 1,900, actual 1,950 → abnormal gain 50 units × 70 = ₹3,500 (debited to the process).
Output = 1,950 × 70 = ₹1,36,500. Process account totals: debit 1,35,000 + 3,500 = ₹1,38,500 = credit 2,000 + 1,36,500. Units: 2,050 = 2,050.
Abnormal Gain A/c is debited with scrap value forgone 50 × 20 = ₹1,000 → ₹2,500 net gain to Costing P&L.

Example 3 - Equivalent production: FIFO versus weighted average. Opening WIP 1,000 units (material 100% complete ₹30,000; labour 60% ₹3,000; overhead 60% ₹1,800 - total ₹34,800). Introduced 9,000 units. Completed and transferred 8,000 units. Closing WIP 2,000 units (material 100%, labour and overhead 50%). Current costs: material ₹1,80,000; labour ₹42,000; overhead ₹25,200.

Equivalent units	Material	Labour	Overhead
FIFO: complete opening WIP	0	400	400
FIFO: started and completed (8,000 − 1,000)	7,000	7,000	7,000
Closing WIP	2,000	1,000	1,000
FIFO total EU	9,000	8,400	8,400
Weighted average (8,000 completed + closing WIP EU)	10,000	9,000	9,000

FIFO rates: material 1,80,000 ÷ 9,000 = ₹20; labour 42,000 ÷ 8,400 = ₹5; overhead 25,200 ÷ 8,400 = ₹3 → ₹28 per unit of current work.
FIFO valuation: opening WIP completed = 34,800 + 400×5 + 400×3 = ₹38,000 (1,000 units); started and completed = 7,000 × 28 = ₹1,96,000; transferred out = ₹2,34,000 (average ₹29.25); closing WIP = 2,000×20 + 1,000×5 + 1,000×3 = ₹48,000. Total ₹2,82,000.
Weighted average rates: material (30,000+1,80,000) ÷ 10,000 = ₹21; labour 45,000 ÷ 9,000 = ₹5; overhead 27,000 ÷ 9,000 = ₹3 → ₹29 per unit.
WA valuation: transferred 8,000 × 29 = ₹2,32,000; closing WIP = 2,000×21 + 1,000×5 + 1,000×3 = ₹50,000. Total ₹2,82,000 (= opening ₹34,800 + current ₹2,47,200, so both methods reconcile).
Material cost fell from ₹30 to ₹20 a unit, so FIFO pushes the older, dearer cost into transfers and leaves cheaper current cost in WIP; weighted average splits the difference.

Example 4 - Joint product apportionment. A process costing ₹3,60,000 yields A 4,000 litres (₹60/litre), B 6,000 litres (₹30/litre), C 2,000 litres (₹30/litre), all saleable at split-off.

Product	Litres	Price ₹	Sales value ₹	Physical-units basis ₹	Sales-value basis ₹
A	4,000	60	2,40,000	1,20,000	1,80,000
B	6,000	30	1,80,000	1,80,000	1,35,000
C	2,000	30	60,000	60,000	45,000
Total	12,000	-	4,80,000	3,60,000	3,60,000

Physical basis = ₹3,60,000 ÷ 12,000 = ₹30/litre; sales-value basis = 3,60,000 ÷ 4,80,000 = 0.75 of each product's sales value.
On the physical basis A shows a margin of 2,40,000 − 1,20,000 = ₹1,20,000 while B shows nil; on the sales-value basis every product shows the same 25% margin. The "profit" of a joint product is therefore an artefact of the basis chosen.
If a by-product also arises and realises ₹8,000 net, the joint cost to apportion falls to ₹3,52,000.

Example 5 - Further processing and inter-process profit. C above can be refined at ₹8/litre and sold at ₹36/litre.

Incremental revenue = 2,000 × (36 − 30) = ₹12,000; incremental cost = 2,000 × 8 = ₹16,000 → do not refine (loss ₹4,000). The ₹45,000 joint cost allocated to C is irrelevant here.
Inter-process profit: Process I transfers output costing ₹2,00,000 at cost plus 25% = ₹2,50,000; Process II holds closing stock of ₹50,000 of this transfer. Unrealised profit = 50,000 × (50,000 ÷ 2,50,000) = ₹10,000, which is removed from stock in the balance sheet.

Where it is used

Sugar mills (Balrampur Chini, Shree Renuka): cane crushing, clarification, crystallisation and centrifuging as processes; bagasse and molasses as by-products; yield and recovery percentage tracked daily.
Petroleum refining (IOCL, BPCL, Reliance): crude is a classic joint-cost case - petrol, diesel, ATF, LPG, naphtha and bitumen all split off from the same crude feed.
Cement, fertiliser and chemicals (UltraTech, Ambuja, IFFCO, Tata Chemicals): kiln, grinding, packing or reactor-wise process costs per tonne, maintained in CRA-1 format for cost audit.
Pharmaceuticals and FMCG (Sun Pharma, Cipla, HUL, Dabur, Amul): granulation, compression, coating, filling and packing processes with batch yields and in-process rejection analysis.
Steel, paper, textiles and paints (Tata Steel, JK Paper, Asian Paints, Arvind): blast furnace to rolling, pulping to finishing, spinning to weaving to dyeing - each a process with its own normal loss norm.
Job roles: cost accountant and plant finance analyst (process cost sheets, yield and loss variance), MIS and FP&A analyst (per-tonne cost dashboards), internal auditor and cost auditor, ERP functional consultant configuring product costing in SAP CO-PC or Oracle.

Interview questions

Q: How does process costing differ from job costing? A: Process costing averages period costs over homogeneous continuous output collected process-wise, while job costing traces actual costs to a specific identifiable job or order.
Q: Why is normal loss credited to the process account only at scrap value? A: Normal loss is inherent and unavoidable, so its cost must be absorbed by the good units; only the money actually realised from the scrap is credited, which reduces the cost borne by good output.
Q: Why are abnormal loss and gain valued at the normal cost per unit? A: Because the abnormal event should not alter the product's cost - valuing abnormal items at the normal rate keeps the process cost comparable and isolates the abnormal effect in the Costing P&L.
Q: How is abnormal gain recorded? A: It is debited to the process account in units and value at normal cost per unit, credited to Abnormal Gain A/c, which is then debited with the scrap value of the normal loss not realised; the balance goes to Costing P&L.
Q: What is equivalent production and why is it needed? A: It expresses part-finished units as an equivalent number of complete units so that period cost can be split fairly between output transferred and closing WIP.
Q: FIFO or weighted average - which gives a better cost for control? A: FIFO, because it divides only the current period's cost by the current period's equivalent units, so the unit cost is not contaminated by last period's prices; weighted average is simpler and smooths fluctuations.
Q: Why do firms transfer between processes at cost plus a margin? A: To make each process accountable as a quasi profit centre and to compare its output price with the market, which supports make-or-buy decisions; the resulting unrealised profit in stock must be eliminated for financial reporting.
Q: How do you distinguish a joint product from a by-product? A: By relative sales value and management intent - joint products have comparable significant value and are the purpose of the process, while a by-product is incidental and of minor value.
Q: A product allocated joint cost shows a loss. Should it be discontinued? A: Not on that basis - joint cost allocation is arbitrary and the output is inseparable; the only valid test is whether its incremental revenue after split-off exceeds its separable costs.
Q: How does Ind AS 2 affect process cost figures? A: Inventory must be valued at the lower of cost and net realisable value, with normal overheads at normal capacity included but abnormal loss, idle capacity and selling cost excluded.
Q: At what degree of completion are abnormal loss units taken in equivalent production? A: At the stage where the loss is detected - taken as 100% complete unless the question specifies an inspection point, while normal loss units are ignored altogether.
Q: Where would you check whether a sugar or cement company must maintain process-wise cost records? A: In the Companies (Cost Records and Audit) Rules, 2014 under section 148 of the Companies Act, 2013, and the CRA-1 formats; the industry lists and turnover thresholds have been amended, so the current version must be referred to.

Common mistakes

Dividing total cost by input units instead of (input − normal loss), or charging cost to normal loss units.
Forgetting to credit the scrap realisation of abnormal loss units, or forgetting to debit Abnormal Gain A/c with the scrap value forgone.
Showing abnormal gain on the credit side of the process account - it belongs on the debit side in both units and value.
Applying one completion percentage to all elements, instead of separate equivalent units for material and for conversion cost.
Mixing methods: using opening WIP cost in the numerator while using FIFO equivalent units in the denominator.
Allocating joint cost on sales value after further processing without deducting separable costs - the NRV adjustment is compulsory.
Treating allocated joint cost as relevant in a further-processing or product-dropping decision, and leaving inter-process unrealised profit inside closing stock.