How Do I Build a WIP Schedule for My Construction Company?
By Aaron Mills, Founder and CEO
You build a Work In Progress (WIP) schedule by listing every active job, comparing what you’ve earned to date against what you’ve billed to date, and tying that back to your cost-to-complete estimate so you can see whether each job is underbilled, overbilled, or drifting off target.
A useful WIP schedule only works when the inputs are current. That means approved change orders, clean job costs, posted billings, and an honest estimate of what it’ll take to finish each job.
Why a WIP Schedule Matters in Construction
A WIP schedule connects job performance, billing timing, and financial reporting. Without it, your income statement can look fine while cash feels tight, or a project can seem healthy until the final margin tells a different story.
For contractors, WIP is one of the main controls that keeps the books tied to field reality. It helps you see whether billing is keeping up with production, whether job costs are being coded correctly, and whether your gross profit assumptions still hold up once work is underway.
That matters for general contractors, specialty contractors, and trades like electrical, HVAC, plumbing, roofing, concrete, excavation, masonry, millwright, landscaping, painting, and carpentry. The job type changes, but the core question stays the same: are your financial statements telling the truth about the work in progress?
What Should Be Included in a WIP Schedule?
Start with active contracts only. Then build one line per job and fill in the core fields that tell you what has happened, what remains, and whether your billing position matches progress.
At a minimum, your WIP schedule should include these columns:
| WIP Field | What to Enter | Why It Matters |
| Job Name or Number | Each active contract | Keeps reporting tied to the field and your accounting system |
| Contract Value | Original contract plus approved change orders | Sets the revenue ceiling you’re measuring against |
| Estimated Total Cost | Your current best estimate to finish the job | Drives percent complete and earned revenue |
| Costs Incurred to Date | Actual job costs posted so far | Shows how much of the estimate has been consumed |
| Percent Complete | Costs incurred divided by estimated total cost | Gives you the production-based completion measure |
| Earned Revenue to Date | Contract value multiplied by percent complete | Shows what revenue should be recognized so far |
| Billings to Date | What you’ve invoiced the customer so far | Lets you calculate overbillings or underbillings |
Once you’ve got that structure, the math is straightforward:
Percent complete = costs incurred to date ÷ estimated total cost
Earned revenue = contract value × percent complete
Overbilling or underbilling = billings to date minus earned revenue
You’re overbilled when billings are higher than earned revenue. You’re underbilled when earned revenue is higher than billings. Either position can be explainable, but both deserve attention because they affect cash timing and job visibility.
The bigger issue is whether the data behind the schedule is current and credible.
Check out this free WIP cheat sheet to help you make sense of your numbers and spot issues earlier.
What Inputs Do You Need Before the Math Means Anything
The formulas aren’t the hard part. The real work is making sure the schedule is built on numbers your team can trust.
Your contract value should reflect approved change orders. Verbal approvals, expected claims, and “probably coming” revenue should be tracked separately so the WIP doesn’t overstate the job.
Your estimated total cost should reflect the job as it exists today. Many contractors leave the original estimate untouched even after labor, materials, scope, or schedule conditions change. That makes the percent complete calculation look precise while the actual job story has already moved.
Your costs incurred to date should be posted cleanly and consistently. Labor, materials, equipment, subcontractors, burden, and other job costs need to hit the right job. Bad cost coding can distort percent complete and make a healthy job look troubled, or make a troubled job look fine.
Your billings to date should tie to posted invoices in the accounting system. Draft invoices and billing plans are useful for discussion, but they shouldn’t be treated as billings in the WIP schedule.
How Should You Review a WIP Schedule?
A WIP schedule becomes more useful when you review it job by job instead of only looking at the total. Start with the jobs that show large overbillings, large underbillings, or margin changes from the original estimate.
Then ask what’s causing the movement. A labor-heavy job may be burning hours faster than expected. A billing issue may mean production is ahead of invoicing. A margin change may point to estimating assumptions, project management issues, field execution, or missing change order discipline.
A monthly review works best because it creates a regular cadence. Your accounting team, project managers, estimator, controller, and owner should be working from the same job assumptions. When those groups are using different versions of the truth, the WIP schedule won’t be reliable.
Book a conversation here if you want more structure around WIP, reporting, and financial decision-making.
Common WIP Schedule Mistakes That Create Bad Decisions
Most WIP problems build gradually. In many cases, the issue is not one major error, but several smaller habits that make the schedule less reliable over time.
One common mistake is treating WIP as something the accounting team handles alone. Accounting may own the report, but the schedule depends on current information from operations and project management. The people managing the work often have the clearest view of changing job conditions, labor issues, scheduling delays, and revised expectations.
Another issue is leaving the original estimate in place long after the job has changed. When the estimate at completion doesn’t reflect current job conditions, the reported margin can look stronger than the job actually is. That makes it harder to spot problems early enough to respond.
I also see problems when job costs come from a system that doesn’t tie closely to the accounting records. When job costing and financial reporting are out of sync, confidence in the WIP schedule starts to erode because the numbers no longer tell one consistent story.
I also suggest evaluating jobs individually. Two underbilled jobs can look similar on the surface while pointing to very different issues. One may be waiting on a billing milestone, while another may be showing estimate drift, labor overruns, or weak cost control. The schedule becomes much more useful when you look past the total and understand what’s happening job by job.
What to Do After You Build the Schedule
Once you’ve built the WIP schedule, the next step is to use it in a consistent way. A WIP schedule should help you evaluate margin trends, billing timing, estimating accuracy, and where project management attention is needed most.
It should also help you make your monthly financial statements more dependable. When WIP is updated and reviewed on a regular cadence, it gives your leadership team a stronger basis for discussing job performance and deciding what needs attention next.
That’s where the value really comes from. A solid WIP process gives you a clearer view of how jobs are performing and where pressure is building, so you can respond while there’s still time to do something about it.
Book a discovery call here if you want help building a more reliable WIP process.
What to Expect When You Tighten Up the WIP Process
A stronger WIP process usually follows a simple rhythm:
- Gather active jobs and confirm contract values.
- Update estimated total cost with current field input.
- Confirm job costs are posted to the right projects.
- Tie billings to posted accounting records.
- Review overbillings, underbillings, and margin movement.
- Assign follow-up actions for jobs that need attention.
This rhythm helps turn WIP into a management tool. You’re no longer just closing the month. You’re seeing where cash pressure, billing gaps, and job margin issues are starting to build.
Signs You Need Help With Your WIP Schedule
You may need a stronger WIP process when your project managers and financial statements tell different stories. The same is true when gross profit swings heavily from month to month, underbillings are hard to explain, or estimated margins don’t hold once the job gets moving.
A WIP schedule also needs attention when the accounting team can close the month but the owner still doesn’t trust the numbers. That’s usually a sign that job costing, billing, accruals, or cost-to-complete estimates need a more disciplined process.
FAQs About Building a WIP Schedule for Your Construction Company
What Is a WIP Schedule in Construction Accounting?
A WIP schedule is a job-by-job report that compares costs incurred, estimated total cost, earned revenue, and billings to date. It helps you see whether each active project is overbilled or underbilled and whether expected margins are still holding up.
How Often Should I Review WIP as a Contractor?
You should review WIP monthly, usually as part of your close process. A monthly review makes it easier to catch margin drift, billing delays, and job issues before they create bigger cash flow problems.
How Do I Calculate WIP for a Construction Company?
Most contractors calculate WIP using percent complete. You divide costs incurred to date by estimated total cost, apply that percentage to the contract value to determine earned revenue, and then compare earned revenue to billings to date.
Why Doesn’t My WIP Match My Financial Statements?
That usually points to input or timing problems. Outdated job estimates, incomplete cost postings, missing change orders, and billings that haven’t been posted can all cause the WIP schedule and the financial statements to tell different stories.
Is WIP the Same as Backlog?
No. Backlog refers to work you’ve sold but haven’t completed yet. WIP focuses on jobs that are already in progress and measures how much has been earned, billed, and spent so far.
How Do I Analyze a WIP Schedule?
Start by reviewing large underbillings, large overbillings, and jobs where expected margin has changed. Then look at the reason behind each one, whether that’s billing timing, estimating, labor performance, or overall job execution.
A Better WIP Process Leads to Better Decisions
If you’re building a WIP schedule for your construction company, start with the core fields, make sure your job assumptions are current, and review the schedule monthly with the people who know the work best. What matters most is whether the schedule reflects actual job performance, a realistic cost to complete, and billings that tie back to your accounting records.
When the process is working well, you can see job performance more clearly, trust your financial statements more, and catch issues sooner. And when you need help putting that monthly review process in place, the right financial support can make the schedule much more useful.
When you’re ready for more clarity around job performance and financial reporting, schedule your conversation here.
