What Is WIP Accounting?
Work in process (WIP) is the accumulated cost of products that have started production but are not finished. On the shop floor it is a pile of partly built units. In the ledger it is an inventory asset, and it holds every dollar of material, labor, and overhead charged to open work orders.
WIP accounting is the discipline of tracking those costs as they build up, then moving them out at the right time: to finished goods when a work order completes, and to cost of goods sold (COGS) when the product is sold.
It is a timing account. If costs enter late, leave late, or never leave, the balance sheet overstates assets and the income statement misstates margin for the period.
What Goes Into WIP
Every work order collects three kinds of cost. Material and labor are traced directly to the order. Overhead is allocated to it.
- Direct material: components issued from stock against the bill of materials. Issued quantity, not planned quantity, drives the cost.
- Direct labor: operator time booked against routing operations, valued at a labor rate.
- Manufacturing overhead: indirect production costs such as utilities, equipment depreciation, and supervision, applied at a predetermined rate.
Accounting standards (ASC 330 and IAS 2) are consistent on the principle: inventory cost includes costs directly attributable to bringing goods to their present condition. They also say what stays out. Abnormal waste and the cost of idle capacity are expensed, not capitalized.
Include in WIP
- Material issued to the work order
- Direct labor booked to operations
- Applied production overhead
- Normal scrap and yield loss
- Costs of outside processing steps
Keep Out of WIP
- Raw materials not yet issued
- Units already completed and received into stock
- Abnormal scrap, rework, or spoilage
- Cost of abnormally idle capacity
- Selling and general admin overhead
How WIP Accounting Works
The WIP balance follows a simple roll-forward:
Ending WIP = Beginning WIP + Direct material + Direct labor + Applied overhead − Cost transferred to finished goods
The formula is easy. The difficulty is that each input comes from a different team and posts on a different schedule. Stores issues material, operators book time, and finance sets the overhead rate. WIP is accurate only when all three feed the same work order at the time the work happens.
Choosing an Overhead Application Base
Overhead is the one cost layer you cannot trace to a work order, so you apply it using a rate. The right base is the driver that best explains why overhead is incurred.
- By direct labor hoursBest for labor-intensive work such as manual assembly, where overhead tracks the time people spend on the order.
- By machine hoursBest for automated or capital-heavy production, where depreciation and power are driven by run time, not headcount.
- By direct material costUseful when overhead such as handling and storage scales with the value of material consumed.
- By units producedWorks for single-product lines where every unit consumes roughly the same overhead.
The common mistake is picking one base for the entire plant. A labor-hours rate applied to a highly automated line over-costs the labor-light products and under-costs the machine-heavy ones, and your product costs inherit the error.
A Worked Example
A manufacturer releases a work order for 100 assembled units. Material is issued in full when production starts. Labor is booked over two months, and overhead is applied at $20 per direct labor hour.
Material issued up front; labor valued at $30 per hour; overhead applied at $20 per direct labor hour.
Here is how the journal entries and the WIP balance move:
Unit cost is $8,000 ÷ 100 = $80. Sixty units sold at $80 = $4,800 COGS; $3,200 remains in finished goods.
At the end of month 1, the WIP account holds $6,500: $4,000 of material plus $2,500 of conversion cost, with no finished unit to show for it. At the end of month 2 the order completes, the $8,000 transfers to finished goods, and WIP returns to zero.
Why Recording It Correctly Matters
Now suppose the team expenses labor and overhead as they are incurred instead of capitalizing them into WIP. Month 1 shows $2,500 of cost with no revenue behind it. In month 2, finished goods are valued at material only, $40 per unit, instead of $80.
If you sell those units for $110 each, the margin looks very different:
- Correct WIP accounting: ($110 − $80) ÷ $110 = 27.3% margin
- Conversion costs expensed early: ($110 − $40) ÷ $110 = 63.6% margin
Same product, same price. One version tells you the product is healthy; the other has quietly moved half the cost into the wrong month.
WIP is not a place costs live. It is a place they pass through, and every delay in passing distorts the period.
Applied vs Actual Overhead
Overhead is applied at a predetermined rate, but actual spend never matches it exactly. If a plant incurs $52,000 of actual overhead in a month and applies $48,000 to work orders, overhead is under-applied by $4,000.
That $4,000 does not belong in WIP. Most manufacturers close a small variance to COGS at period end. A large one should be allocated across WIP, finished goods, and COGS in proportion to the overhead each holds. Either way, the variance should be visible and explained, not buried in an inventory balance. How the cost of units is then relieved at sale depends on your costing method, covered in our guide to inventory valuation methods.
The Timing Problem: Costs That Post Late
In a perfect system, every material issue, labor entry, and overhead charge would post the moment it happens. In reality, labor is entered at the end of a shift or week, and overhead rates are only trued up when the books close. By then, partly finished goods have moved on.
Well-run finance teams handle this in two steps:
- Apply at standard during the month. Post labor and overhead using standard rates as work is reported, so open work orders carry a realistic cost.
- True up at close. Compare applied to actual, then post the variance to COGS or allocate it across WIP, finished goods, and COGS.
Done manually, this is where spreadsheets take over: someone exports work orders, estimates labor, and posts journal entries at month end, long after the product mix and pricing decisions were made.
Common WIP Accounting Mistakes
- Leaving work orders open. Completed or cancelled orders that stay open keep cost in WIP that should be in finished goods or written off.
- Booking labor in batches. Time entered after month end lands in the wrong period and understates WIP when it matters.
- Absorbing scrap silently. Normal scrap belongs in product cost. Abnormal scrap should be expensed so it stays visible.
- Mishandling partial completions. Transferring all the cost, or none of it, when only part of a batch is finished misstates both WIP and finished goods.
- Never revisiting overhead rates. A rate set a year ago drifts away from real spend, and every work order carries the error.
- Skipping the subledger tie-out. If open work order cost does not match the general ledger WIP balance, the difference is a problem waiting for the auditor.
A Month-End WIP Checklist
- Tie subledger to ledgerTotal cost on open work orders should equal the WIP general ledger balance.
- Review aged ordersFlag anything open past its expected cycle time and close or cancel it.
- Check for negative WIPCompletions that exceed issued cost usually mean missing material or labor postings.
- Clear completed ordersA closed work order should carry no balance. Any remainder is a variance to explain.
- Settle overheadCompare applied to actual and decide where the variance goes.
How an ERP Should Handle WIP
WIP sits where three teams meet: planning releases the order, the shop floor consumes material and time, and finance owns the ledger. When those teams work in separate systems, nobody owns the full number. An ERP should connect them so that:
- Work orders inherit materials and operations from the bill of materials and routing, so standard cost is known before production starts
- Material issues and labor reported on the shop floor post to the work order as they happen
- Overhead is applied automatically using the rates and bases you define
- Completions move cost to finished goods in inventory, and variances are flagged for review at close
Axolt runs production planning, inventory, and finance on one data model inside Salesforce. A material issue updates the work order and the WIP balance in the same transaction, so there is no overnight sync and no month-end reconciling item to chase. That is the idea behind real-time manufacturing finance: the margin you see mid-month is built on the actual cost of the work in progress, not a guess.
Frequently Asked Questions
Is WIP the same as raw materials inventory?
No. Raw materials are components still in stock. They become WIP only when they are issued to a work order, and WIP also includes the labor and overhead added during production.
When does WIP become finished goods?
When a work order completes and the units are received into stock. The accumulated cost transfers from WIP to finished goods, and moves to COGS when the units are sold.
How is manufacturing overhead applied to WIP?
Most manufacturers use a predetermined rate tied to a driver such as direct labor hours or machine hours. The applied amount is debited to WIP and credited to an overhead applied account.
How often should WIP be reconciled?
At least monthly, before close. Compare the open work order subledger to the general ledger WIP balance, and investigate aged, negative, or completed work orders that still carry cost.
The Bottom Line
WIP accounting is not about posting more journal entries. It is about making sure every dollar issued to a work order is visible, attributed to a product, and moved out on time.
The arithmetic is not complicated. What makes it hard is that the costs come from different teams on different schedules. The manufacturers who get it right are the ones whose planning, shop floor, and finance data live in one place.
See Work Order Costs in Real Time
Axolt connects work orders, inventory, and finance on Salesforce, so WIP, finished goods, and COGS update as production happens.
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