1. Your invoices do not tell you what you earned
A strong billing month can make a contractor’s income statement look better than the jobs actually performed. A slow billing month can make profitable work look weak. If your reports treat every invoice as earned revenue, the timing of pay applications can distort the profit you use to make hiring, equipment, and owner distribution decisions.
WIP accounting separates what you billed from what you earned on unfinished contracts. WIP stands for work in progress. For contracts recognized over time, a WIP schedule helps match revenue to progress and the costs associated with that work. The right accounting treatment depends on your contracts and reporting requirements; the examples below use a cost-to-cost measure of progress.
Over- and under-billings do not create or destroy the underlying economics of a job. They identify differences between billing and earned revenue. Correcting those differences can change reported profit substantially, especially when your books currently recognize invoices as revenue without a WIP adjustment.
2. Start with a credible estimate of the cost to finish
A useful WIP schedule starts with job-level information, not just the general ledger balance. For each open contract, you need the current contract value, costs incurred, estimated remaining costs, and billings through the same cutoff date. If costs stop at Friday but billings include the following week, your comparison is already off.
Under a basic cost-to-cost approach, estimated total cost equals costs incurred plus estimated cost to complete. Dividing costs incurred by estimated total cost gives the percentage complete. Multiply that percentage by contract value to calculate earned revenue. Earned revenue minus costs incurred gives gross profit to date—not company net profit after overhead.
The formula is straightforward. The estimate is where judgment matters. A stale budget can make a troubled job appear profitable. Ask the project manager what labor, materials, subcontractor work, equipment, rework, and closeout costs remain. Do not simply subtract spending from the original budget and assume the remainder will finish the job.
Cost-to-cost also requires appropriate inputs. Large material purchases, stored materials, and unusual costs may need special treatment because spending does not always represent installed progress. Establish a consistent method with your accounting advisor.
- Keep contract values and change orders supported; do not count disputed extras as certain revenue.
- Capture incurred costs, including subcontractor work performed but not yet invoiced.
- Update remaining costs based on field conditions, not the profit margin you hope to report.
3. Overbilling can make cash look like profit
Consider a $1,000,000 contract with estimated total costs of $800,000. You have incurred $320,000 in costs. Using the simplified cost-to-cost method, the job is 40% complete, earned revenue is $400,000, and gross profit to date is $80,000.
Now assume you have billed $500,000. Billings exceed earned revenue by $100,000, so the job is overbilled. If the books show all $500,000 as revenue against $320,000 in costs, they show $180,000 in gross profit. The WIP adjustment reduces revenue by $100,000, bringing gross profit back to $80,000.
The overbilling is generally presented as a contract liability, often labeled billings in excess of costs and estimated earnings. It reflects billing ahead of performance, not another pot of profit. Also, billed does not mean collected: an overbilled job can still have unpaid receivables and a cash shortage.
Billing ahead can help fund construction when the contract permits it. The risk is spending those collections as though the related work is already finished. Before taking distributions or buying equipment, review the remaining job costs and your cash forecast. An overbilling balance is not an exact cash reserve requirement, but it is a warning against treating the bank balance as spendable earnings.
4. Underbilling can hide profit—and expose a collection problem
Use the same job, with $400,000 in earned revenue and $320,000 in incurred costs, but assume billings are only $350,000. The job is underbilled by $50,000. An invoice-based report would show $30,000 in gross profit. The WIP adjustment adds $50,000 of earned revenue, bringing gross profit to $80,000.
That underbilling is generally presented as a contract asset, often labeled costs and estimated earnings in excess of billings. It is not cash, and it is not automatically an amount you can invoice today. Your right to bill may depend on a milestone, approval, or another contract condition.
Some underbillings reflect normal timing. Others point to missed pay applications, unresolved scope, or an overly optimistic cost estimate. If the same balance remains month after month, find out why. Recording earned revenue does not solve the billing or collection issue.
Track retainage separately rather than assuming it is the cause of every underbilling. Retainage may already be included in billed amounts but withheld from payment. Its presentation depends on the contract and payment conditions.
- Identify the specific work or contract condition behind each material underbilling.
- Assign an owner and expected billing date where the amount is billable.
- Confirm contract-rights questions with your attorney instead of assuming disputed work is collectible.
5. Read changes in margin alongside the billing position
An overbilled job is not necessarily profitable, and an underbilled job is not necessarily losing money. Billing position measures timing. Estimated margin measures job economics. You need both to understand performance.
Return to the $1,000,000 job with $320,000 in incurred costs and $500,000 billed. Suppose estimated total cost rises from $800,000 to $900,000. Progress falls to about 35.6%, earned revenue falls to about $355,556, and gross profit to date falls to about $35,556. Overbilling increases to about $144,444. Nothing changed in invoices or cash; the revised cost forecast revealed lower profit.
This is why a monthly WIP review should include operations and accounting. Reconcile the schedule to the books, challenge cost-to-complete estimates, and explain meaningful changes before relying on the income statement. If a job is expected to lose money overall, raise it promptly with your accounting advisor; loss recognition can require more than the basic calculation shown here.
- Compare current estimated margin with both the original estimate and last month’s forecast.
- Investigate large or aging underbillings and significant billing-ahead positions.
- Review job gross profit separately from company overhead and net profit.
- Use a cash forecast alongside WIP; earned revenue does not pay next week’s bills.
When to get help
Get help when you cannot connect job profit to the income statement, cost-to-complete estimates are rarely updated, or billing adjustments cause unexplained monthly swings. The first step may be as simple as agreeing on a cutoff date, cleaning up job costs, and reviewing your largest open contracts.
A 20-minute financial review with Contractor Plus Books can help you see where your numbers stand and identify gaps in your WIP reporting, job costing, or cash planning. There is no need to rebuild everything at once. Start with the information that affects your next decision. Contractor Plus Books is not a CPA firm; confirm tax questions with your CPA and legal questions with your attorney.
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