WIP Accounting: How It Works, Formula & Example

WIP accounting, or work in progress accounting, is the process construction businesses use to match the revenue they have actually earned with the costs incurred and progress achieved on jobs that are still underway. In practical terms, a WIP report answers a question your bank balance cannot: how much profit have we genuinely earned on each active project so far?

For an Australian contractor, builder or subcontractor, that normally means comparing the current contract value, costs to date, estimated total cost, percentage complete, revenue recognised and progress claims issued. If a $2.4 million contract is assessed as 50% complete, for example, the business may have earned about $1.2 million of revenue even if it has invoiced a different amount. The gap between earned revenue and billings is what exposes underbilling or overbilling.

There is an important accounting qualification. Under AASB 15 Revenue from Contracts with Customers, revenue is recognised as the relevant performance obligation is satisfied. For performance obligations satisfied over time, progress can be measured using appropriate input or output methods. Cost-to-cost is common in construction, but it is not a licence to treat every dollar spent as progress. ^[1]

If your problem is not understanding WIP, but finding enough finance capacity to keep job costs, invoices, reconciliations and monthly reporting current, that is where Cost Solution can help. We do not replace your Australian accountant, provide tax advice or sell one-off WIP reports. We help construction businesses recruit a dedicated Filipino accounting professional who works inside their existing systems and processes, with potential staffing cost savings of 50% to 70% compared with an equivalent local role.

What does WIP accounting actually measure?

Construction WIP accounting measures the financial position of work that has started but is not yet complete. Rather than allowing invoices or cash receipts to dictate reported performance, it compares what has happened commercially with what has happened operationally.

A useful WIP schedule should tell you, project by project:

• the original contract value;
• approved variations or contract modifications;
• the latest expected total project cost;
• actual costs incurred to date;
• the estimated cost to complete;
• percentage complete;
• revenue earned or recognised to date;
• revenue previously recognised;
• revenue to recognise in the current period;
• progress claims or billings to date;
• underbilling or overbilling;
• forecast gross profit and gross margin.

This is why wip construction reporting should not sit in an isolated finance spreadsheet. The quality of the accounting depends on job-cost coding, updated forecasts, variation status, subcontractor commitments and real information from the project team.

“Revenue for contractors is not generated by requisitioning a customer. Revenue is generated through a calculation, the percentage of completion.”

Rob Mercado, CPA, CCIFP, Managing Director at CBIZ, quoted by AICPA & CIMA ^[2]

How to calculate WIP accounting in construction

For a project where a cost-based input method faithfully represents progress, the basic WIP calculation can be built in four steps.

1. Calculate the latest estimated total cost

Do not automatically use the tender budget. WIP should use the best current estimate of what the project is expected to cost when finished.

Estimated total cost = Costs to date + Estimated cost to complete

If the original budget was $1.80 million but procurement changes, labour productivity and subcontractor pricing now indicate a final cost of $1.92 million, your WIP calculation should not pretend the old estimate still exists.

2. Calculate percentage complete

Under the cost-to-cost approach:

Percentage complete = Costs incurred to date ÷ Estimated total cost

If costs to date are $960,000 and the current estimated total cost is $1.92 million:

$960,000 ÷ $1,920,000 = 50%

3. Calculate earned revenue

For a simplified example:

Earned revenue to date = Current contract value × Percentage complete

On a $2.4 million contract at 50% completion:

$2,400,000 × 50% = $1,200,000 earned revenue

4. Compare earned revenue with billings

Now compare cumulative revenue earned with cumulative progress claims.

Underbilling or overbilling = Earned revenue to date – Billings to date

If the contractor has billed $1.08 million:

$1,200,000 – $1,080,000 = $120,000 underbilled

The arithmetic is easy. The difficult part is deciding whether the $1.92 million estimated final cost, $2.4 million contract value and $960,000 cost-to-date figure are actually trustworthy.

Underbilling and overbilling are not the same as profit and loss

Underbilling means earned revenue is higher than the amount billed to the customer. You may have delivered more work than you have claimed. This can create working-capital pressure because the business is effectively financing part of the project.

Overbilling means billings are ahead of earned revenue. That can improve short-term cash flow, but the difference is not additional profit. It represents billing ahead of the recognised performance position and needs to be understood accordingly.

A good WIP review therefore asks two separate questions: Are we making the expected margin? and Are our progress claims keeping pace with the work? Those questions are related, but they are not interchangeable.

How AASB 15 changes the way Australian contractors should think about WIP

One of the biggest problems with online WIP guidance is that much of it is written for the United States. Australian businesses should be careful with articles that present percentage-of-completion accounting and the completed-contract method as if they were simply two interchangeable choices.

Under AASB 15, the first question is whether a performance obligation is satisfied over time or at a point in time. One over-time criterion applies where the entity’s performance creates or enhances an asset controlled by the customer as that asset is created or enhanced. Another can apply where the asset has no alternative use to the entity and there is an enforceable right to payment for performance completed to date. ^[1]

Where revenue is recognised over time, AASB 15 allows progress to be measured using methods that faithfully depict performance, including input methods based on factors such as resources consumed, labour hours or costs incurred.

But there is a catch that matters enormously for WIP accounting.

Cost incurred does not automatically equal progress achieved.

AASB 15 specifically notes that input methods can become distorted where an input does not depict the transfer of control. Significant inefficiency, unexpected wasted materials or other costs that do not contribute to satisfying the performance obligation may need to be excluded from the progress measure. Costs that are disproportionately large compared with actual progress can also require adjustment. ^[3]

Consider a contractor that buys a large package of equipment unusually early in the job. If that purchase drives costs to date from 25% to 40% of estimated total cost while physical and contractual performance has barely changed, blindly applying cost-to-cost can accelerate revenue recognition in a way that does not faithfully depict progress.

That is why a reliable WIP meeting needs more than someone exporting numbers from Xero, MYOB, Jobpac, Procore or an ERP. Someone needs to understand what changed inside the job.

Is WIP an asset on the balance sheet?

Sometimes, but the answer is more nuanced than many WIP guides suggest.

For contracts with customers under AASB 15, the balance sheet presentation depends on the relationship between the entity’s performance and the customer’s payment. If performance occurs before the customer pays or before payment becomes due, the balance may be presented as a contract asset. If payment or an unconditional right to payment comes before the relevant goods or services are transferred, the balance may be a contract liability. ^[4]

This matters because the internal WIP schedule and the financial statement label are not necessarily the same thing.

There is another distinction worth making. A property developer constructing homes or land for sale may also have genuine inventory or work in progress within the scope of AASB 102 Inventories. AASB 102 includes property held for resale and work in progress being produced, while costs to fulfil a customer contract that do not give rise to inventory or another asset are dealt with under AASB 15. ^[5]

The WIP report columns that actually matter

A useful construction WIP schedule does not need dozens of decorative metrics. It needs enough information to explain how the current forecast, recognised margin and billing position were reached.

Five WIP accounting errors that can make the report look better than the project

1. Leaving the estimated cost to complete untouched

A WIP report built from a stale original budget is often little more than a mathematically precise version of an old assumption.

The cost-to-complete forecast should incorporate known subcontractor movements, labour productivity, procurement changes, remaining preliminaries, rectification risk and other information available to the project team.

2. Treating unapproved variations as guaranteed revenue

A variation may be commercially expected without automatically deserving the same accounting treatment as an approved amount. Contract modifications and variable consideration need to be assessed in accordance with the relevant contractual facts and AASB 15.

If a project’s margin only survives because the WIP schedule assumes every disputed variation will be recovered in full, management needs to see that risk rather than bury it inside contract value.

3. Missing committed or accrued costs around month end

The general ledger may say $720,000 has been spent while the project team already knows another $90,000 of subcontractor work has been performed but not yet invoiced.

Ignoring cut-off differences can make the project appear less complete, more profitable or both, depending on the reporting method and timing.

4. Allowing large early costs to inflate percentage complete

Major material purchases, equipment packages, mobilisation costs or unusual wastage can distort a cost-based progress calculation. This is precisely why AASB 15 requires the chosen method to depict performance rather than simply reward expenditure. ^[3]

5. Looking only at the current margin, not the movement

A project forecast at 12% gross margin may look acceptable in isolation. If it was forecast at 19% three months ago, however, the important number is the seven percentage-point decline.

WIP should therefore show a margin bridge: what changed since the previous reporting period, how much each change affected final cost or revenue and whether the movement is recurring.

A six-point WIP integrity check for month-end

Before management relies on the WIP schedule, run each material active job through this review. It is designed to expose the problems that a mathematically correct spreadsheet can still hide.

If one of those six questions cannot be answered, the WIP schedule may still balance mathematically while giving management the wrong commercial signal.

Who should be responsible for WIP accounting?

WIP works best when responsibility is split rather than dumped entirely on the accountant.

The finance team should own accounting cut-off, reconciliations, revenue calculations, billings and the integrity of the financial records. The project or commercial team should own operational forecasts, remaining scope, programme implications, procurement risk, variations and cost-to-complete assumptions. Senior management should challenge large margin movements and unusual billing positions.

This connection with Construction Project Management is critical because an accountant cannot accurately forecast a subcontractor package, delay exposure or productivity problem they have never been told about. Likewise, a project manager should not be expected to make technical revenue-recognition decisions without finance oversight.

A dedicated accounting professional can take much of the recurring workload out of this process: maintaining job-cost records, preparing reconciliations, updating reporting packs, checking invoice coding, maintaining schedules and assembling the information your finance manager or external accountant needs for review.

That is also where offshore staffing can make commercial sense. The objective is not to move judgement, approvals or statutory responsibility to the cheapest person available. It is to separate repeatable accounting production from higher-value financial judgement so your Australian team has reliable information without carrying unnecessary local staffing cost.

How often should a construction business update its WIP?

For most businesses managing material active contracts, monthly WIP reporting is a sensible operating cadence because it aligns naturally with management accounts and month-end close.

Higher-risk projects may need commercial forecasting more frequently. That does not necessarily mean posting accounting adjustments every week. It means the project team should not wait for the next month-end meeting to acknowledge that labour productivity collapsed, a variation was rejected or a major package has moved materially above budget.

The more volatile the project, the more dangerous a stale estimate becomes.

WIP accounting is only as accurate as the forecast behind it

“Construction is the industry where profitable businesses go broke.”

Ramy Hanna, Principal & Founder, Trinity Accounting Practice ^[6]

That line captures why WIP matters. Profit, cash flow and billings can tell three different stories at the same point in a construction project.

A strong WIP process reconnects them. It shows how much of the contract has genuinely been earned, whether the latest cost forecast still supports the expected margin and whether progress claims are ahead of or behind performance.

The formula itself takes seconds. The discipline is in maintaining clean job-cost data, challenging the estimated cost to complete, separating approved value from wishful value, reconciling billings and making sure the chosen progress measure still reflects what has actually been delivered.

For financial statements, tax treatment, GST, contract modifications and the application of AASB standards to your particular contracts, obtain advice from an appropriately qualified Australian accountant. For businesses whose bottleneck is the recurring finance workload behind those decisions, Cost Solution can help build the dedicated accounting capacity needed to keep the underlying data current.

WIP accounting FAQs

What does WIP stand for in accounting?

WIP stands for Work in Progress. In construction, it generally refers to the financial measurement and reporting of projects that have started but are not yet complete.

What is the basic WIP accounting formula?

A commonly used cost-based calculation is costs to date ÷ estimated total cost = percentage complete. That percentage can then be applied to the relevant transaction or contract value to calculate earned revenue where the approach is appropriate under the applicable revenue-recognition policy.

Is underbilling always bad?

No. Small timing differences are normal. Persistent or increasing underbilling, however, deserves investigation because it can mean progress claims are lagging, claims are disputed, costs have been recorded before billable milestones or the progress calculation needs review.

Is overbilling profit?

No. Billing ahead of recognised performance can improve cash flow, but it does not create additional economic profit. The business still has an obligation to deliver the remaining work.

Does WIP accounting only matter to accountants?

No. Reliable WIP depends on information from project managers, estimators, contract administrators, commercial managers and finance staff. It is as much a project-control process as an accounting report.