Stop Over and Under Billing: 6 Step Monthly WIP Checklist for Builders
Overbilling means you’ve invoiced clients for more work than you’ve actually completed, which creates a contract liability on your balance sheet. Underbilling means you’ve completed more work than you’ve billed, which creates a contract asset. Both numbers come straight out of your work-in-progress (WIP) schedule, and both directly shape how surety underwriters and lenders judge your financial health.
TL;DR:
- Overbilling occurs when invoices exceed actual work completed, creating a contract liability, while underbilling happens when work surpasses billed amounts, forming a contract asset.
- WIP schedules track contract value, costs, percent complete, and billing to determine over or under billing, directly impacting financial health indicators.
- Common causes of billing variances include outdated estimates, unapproved change orders, misclassified costs, and collection delays, which can signal systemic issues.
- Monthly WIP reconciliation, led by project managers and accounting, is critical for maintaining accurate margins and catching drift before it affects financial statements.
- Integrating field and office data via ERP reduces manual errors, speeds up updates, and improves the accuracy of WIP and margin management.
Table of Contents
- How earned revenue and billed-to-date create the variance
- Reading a WIP schedule and where the numbers land on your financials
- What causes over and under billing, and the red flags to watch
- Why cash flow, sureties, and lenders all read WIP differently
- A monthly checklist to keep WIP accurate and margins intact
- WIP works best as a conversation, not a report
- How an integrated ERP tightens your WIP cycle
- FAQ
- Sources
How earned revenue and billed-to-date create the variance
Earned revenue is the share of total contract value you’ve actually earned based on progress, not what you’ve invoiced. Billed-to-date is simply what’s on your pay applications. The gap between those two numbers is your over or under billing position.
Here’s a simplified walkthrough:
- A contract is worth $1,000,000 with estimated total costs of $800,000.
- Costs incurred to date are $400,000, so percent complete is 50%.
- Earned revenue is 50% of $1,000,000, or $500,000.
- If you’ve billed $550,000 to date, you’re overbilled by $50,000.
- If you’ve billed $450,000 to date, you’re underbilled by $50,000.
Front-loaded schedules of values push billings ahead of actual progress and create overbilling. Slow pay application cycles, retainage holdbacks, and unpriced change orders tend to do the opposite, leaving you underbilled and short on cash. Our progress billing and pay application checklist walks through how schedule of values structure affects this timing.
Reading a WIP schedule and where the numbers land on your financials
A WIP schedule typically includes contract price, costs to date, estimated cost to complete (ETC), percent complete, earned revenue, and billings to date. Each column feeds the next, and the final output, the over or under billing figure, is what reconciles back to your general ledger.
- Contract price: the total value of the signed contract plus approved change orders.
- Costs to date: actual job costs incurred, matched to the correct job and cost code.
- ETC: a current, honest estimate of what’s left to spend, not a stale number from the original budget.
- Percent complete: costs to date divided by costs to date plus ETC.
- Earned revenue: percent complete multiplied by contract price.
A WIP schedule lists contract price, costs to date, estimated cost to complete, percent complete, earned revenue, and billings to date, with overbillings posting as a contract liability and underbillings as a contract asset. That distinction matters because auditors and lenders read those two lines as proxies for how well your estimates match reality. Reconciling WIP to the GL every month catches coding errors before they compound into a misstated balance sheet. For a deeper look at how this reconciliation supports surety confidence, see our piece on how WIP schedules build trust with sureties.
What causes over and under billing, and the red flags to watch
Most variances start as simple timing mismatches: a pay application cutoff that doesn’t align with cost cutoffs, or a change order that’s done but not yet priced and approved. Left unchecked, though, the same patterns turn into systemic problems.
- Outdated ETC: when estimators don’t revise the cost to complete, percent complete looks better than it is.
- Unapproved change orders: work performed but not billed creates underbilling that hides until closeout.
- Misclassified costs: costs posted to the wrong job or cost code distort percent complete for both jobs involved.
- Collection lags: AR problems don’t change your WIP position, but they turn an overbilled job into a cash problem fast.
Watch for underbilling that grows later in a job’s life, since that’s often margin fade disguised as a timing issue. Also watch for WIP totals that don’t tie to the GL, and for overbilling that’s being used to fund payroll on other jobs rather than sitting as a true liability.
Pro Tip: Track the trend of percent-complete versus billed percent monthly, not just the dollar variance; a widening gap over three months tells you more than any single month’s snapshot.
Why cash flow, sureties, and lenders all read WIP differently
Underbilling ties up working capital you’ve already spent, which strains cash even on a profitable job. Overbilling can do the opposite in the short term, masking a job that’s quietly losing margin until the final billing exposes the shortfall.
- Cash flow: underbilled jobs need financing to cover costs already incurred but not yet collected.
- Sureties and lenders: they track the trend and magnitude of over and underbilling across your WIP as a signal of estimating discipline and cash management, and a sudden swing draws scrutiny fast.
- Audit and tax: your accounting method for long-term contracts affects how these figures flow through, and IRS guidance on construction contract accounting covers the percentage-of-completion and completed-contract methods most contractors rely on.
A job that’s overbilled and slow to collect still drains cash even though the WIP schedule looks fine on paper, so tracking days sales outstanding alongside your billing position matters.
A monthly checklist to keep WIP accurate and margins intact
Treating WIP as a once-a-year accounting chore is how margin fade goes unnoticed for months. A tighter monthly cadence, owned jointly by project managers and accounting, catches drift while there’s still time to act.
- PMs update ETC first, based on current field conditions, not the original budget.
- Confirm every change order’s status: submitted, priced, and approved, or flagged as a dispute.
- Reconcile subcontractor billings and retainage against actual completion percentages.
- Pull field production evidence, like time tickets and progress photos, to support the percent-complete figure.
- Accounting reconciles WIP to the GL and flags any variance before the schedule goes out.
- CFO or controller signs off on the final numbers before they reach ownership or a surety.
Pro Tip: Assign a single owner for ETC updates on every job; when that responsibility is shared or unclear, estimates drift fastest.
Coordinating subcontractor documentation is its own discipline. Resources like this guide on managing flooring subcontractor relationships and this breakdown of rising mechanical subcontractor overhead both point to the same root cause: billing and cost data that doesn’t flow cleanly between field and office. Tighter jobsite coordination, as outlined in this piece on utility contractor coordination, shortens that loop considerably. Technology that connects field data directly to the schedule of values, rather than relying on manual re-entry, shortens this entire cycle and reduces the chance of stale ETC numbers reaching the WIP schedule.
WIP works best as a conversation, not a report
The most reliable WIP schedules come from teams that treat the monthly review as a conversation between the field and the office, not a form to fill out. A project manager who updates ETC honestly, and a controller who checks it against actual cost trends, catches margin fade months before the income statement would show it. Ownership matters more than the software behind it.
— Keith
How an integrated ERP tightens your WIP cycle
A faster WIP cycle starts with field and office data living in the same system instead of three different spreadsheets. Our Construction ERP brings job costing, billing, and field production data into one platform, so percent-complete figures reflect what’s actually happening on site, not what’s leftover from last month’s budget.
- Field updates from our mobile field app feed job costs directly into WIP, cutting manual re-entry.
- AI-driven project management flags cost trends early, helping PMs revise ETC before it drifts too far from reality.
- This significant reduction in manual data entry means less time reconciling spreadsheets and more time reviewing the numbers that matter.
If you’re ready to see how an integrated platform handles WIP, check our pricing page for Essentials, Pro, and Field seat options, or explore the full Construction ERP overview to see how it fits your current billing workflow.
FAQ
Are costs in excess of billings an asset?
Yes, costs and earnings in excess of billings represent underbilling, which is recorded as a contract asset on the balance sheet. It reflects work you’ve completed and earned revenue on but haven’t yet invoiced.
What does “overbilled” mean?
Overbilled means you’ve invoiced a client for more than the percentage of work actually completed, based on your WIP calculation. That excess amount is recorded as a contract liability until the work catches up to the billing.
What does WIP mean in billing?
WIP stands for work-in-progress, and in a billing context it refers to the schedule that tracks contract price, costs to date, percent complete, earned revenue, and billings to date for every active job. The resulting over or under billing figure is what reconciles to the financial statements.
What comes first, revenue or expense?
In construction accounting using the percentage-of-completion method, costs incurred drive the percent-complete calculation, which then determines how much revenue is recognized. In that sense, cost data comes first and earned revenue is calculated from it.