The Construction WIP Report Explained: Over- and Under-Billing

What a WIP report is

A Work-in-Progress schedule lists every open job on one page and reconciles, for each, what you have earned against what you have billed. It is built on the percentage-of-completion method: you recognize revenue as you incur cost, not when you send an invoice.

The reason it exists is that billing and earning rarely line up. You might front-load a pay application to improve cash flow, or fall behind on billing while costs pile up. The WIP report measures that gap and corrects your reported profit so it reflects the work actually done, not the timing of your invoices.

The core calculation

Every WIP line is built from a few inputs and a short chain of math. Walk it in order:

• •Contract value — the current contract amount including approved change orders.
• •Estimated total cost — your latest forecast of what the job will cost (your EAC).
• •Cost to date — actual cost incurred so far.
• •Percent complete = cost to date divided by estimated total cost. This is the cost-to-cost method, the most common basis.
• •Earned revenue = contract value times percent complete.
• •Billed to date — the total you have invoiced the owner, before retainage.
• •Over/under billing = billed to date minus earned revenue. Positive means overbilled; negative means underbilled.

Overbilling vs. underbilling, with example rows

Consider two jobs, each a 1,000,000 dollar contract with an estimated total cost of 800,000 dollars.

Job A is overbilled. Cost to date is 400,000, so it is 50 percent complete and has earned 500,000 dollars of revenue. But you have billed 600,000. Billed minus earned is positive 100,000 — that 100,000 is billings in excess of costs, a liability on your balance sheet. You have collected for work you have not done yet.

Job B is underbilled. Cost to date is also 400,000 — 50 percent complete, 500,000 earned — but you have only billed 350,000. Billed minus earned is negative 150,000. That 150,000 is costs in excess of billings, an asset: work you have done but not yet invoiced. You are essentially financing the owner.

Neither is automatically bad. Modest overbilling is normal and helps cash flow. But heavy overbilling can mean you have borrowed against future work, and underbilling can mean you are leaving cash on the table or are slow to bill — both are signals worth chasing down.

Why bankers and sureties care so much

Your surety underwrites bonding capacity off the WIP report, and your bank lends against it. They are reading it for two warning signs.

The first is profit fade: an estimated total cost that keeps creeping up job over job means your forecasts are optimistic and your margins are thinner than reported. The second is a large, growing overbilling position across all jobs at once. That pattern can mean the company is using tomorrow's billings to cover today's costs — a classic sign of a contractor running on the float of front-loaded jobs. If those jobs slow down, the cash disappears.

• •Profit fade — watch the trend in estimated gross profit from one period to the next on each job.
• •Aggregate overbilling — a big net billings-in-excess figure across the whole portfolio is a liquidity red flag.
• •Underbilling buildup — large costs in excess of billings can signal slow billing or unapproved change-order exposure.

How to keep your WIP honest

A WIP report is only as good as the estimated total cost feeding it, because that one number drives percent complete and therefore earned revenue. If your forecast is stale, your reported profit is fiction. This is why job cost forecasting and WIP accuracy are the same discipline viewed from two seats — the field's EAC is the accountant's input.

Field PM keeps the field and the office on the same numbers: job costing, committed cost, and productivity-based forecasting feed a current estimate at completion, which is exactly the estimated-total-cost figure a clean WIP schedule needs. When the field updates the forecast, the WIP follows instead of drifting.