What Is a WIP Schedule and Why Does It Matter?
A Work-in-Progress (WIP) schedule is a financial report that shows the status of every active construction job in your company. For each project, it compares three things: how much work you have completed, how much revenue you have earned based on that completion, and how much you have actually billed the owner.
The difference between earned revenue and billed revenue determines whether you are overbilled or underbilled on each job. That distinction has profound implications for your financial statements, your cash flow, and your relationship with sureties and lenders.
In traditional retail or service businesses, revenue is recognized when a product is sold or a service is delivered. Construction does not work that way. Projects span months or years, costs are incurred unevenly, and billing follows a schedule that may or may not align with actual progress. The WIP schedule exists to impose financial reality on this complexity.
If you are a GC or specialty contractor and you do not produce a monthly WIP schedule, you do not truly know whether your jobs are making or losing money until they are complete. By then, it is too late to course-correct.
The Percentage-of-Completion Method
Cost-to-Cost Calculation
The most widely used method for determining the percentage of completion on a construction contract is the cost-to-cost method. The formula is straightforward:
Percent complete = Costs incurred to date / Total estimated cost at completion
If a job has a total estimated cost of $500,000 and you have incurred $200,000 in costs to date, the job is 40% complete. If the total contract value is $700,000, you have earned $280,000 in revenue (40% x $700,000), regardless of how much you have billed.
This method relies on two inputs that require discipline: accurate tracking of costs incurred to date and honest estimation of total costs at completion. If either input is wrong, the percentage is wrong, and your entire WIP schedule is unreliable.
When Estimates Change
Construction estimates are not static. Change orders, scope creep, material price increases, subcontractor overruns, and weather delays all affect the total estimated cost. Your WIP schedule must reflect the most current estimate, not the original bid number.
Updating estimates is where many contractors stumble. Project managers are often reluctant to revise estimates upward because it makes their jobs look worse on paper. But a WIP schedule built on stale estimates is worse than useless; it creates a false sense of profitability that collapses when the job closes.
Require project managers to review and certify their cost-to-complete estimates monthly. If a job's total estimated cost has changed, the WIP schedule should reflect it immediately.
Reading the WIP Schedule: Overbilling and Underbilling
Overbilling (Billings in Excess of Costs and Estimated Earnings)
Overbilling occurs when you have billed the owner more than you have earned based on your percentage of completion. For example, if you are 40% complete on a $700,000 contract (earned revenue of $280,000) but you have billed $320,000, you are overbilled by $40,000.
On your balance sheet, overbilling appears as a current liability because you owe the owner $40,000 worth of work that you have been paid for but not yet performed. In cash flow terms, overbilling is favorable because you are holding the owner's money and using it to fund operations.
A moderate level of overbilling is normal and even desirable. It means you are billing ahead of your costs, which keeps cash flowing. However, excessive overbilling can signal problems: front-loading billings to cover cash shortfalls on other jobs, or billing for work that has not actually been started.
Underbilling (Costs and Estimated Earnings in Excess of Billings)
Underbilling is the opposite: you have earned more revenue than you have billed. Using the same example, if you are 40% complete (earned revenue of $280,000) but have only billed $240,000, you are underbilled by $40,000.
On your balance sheet, underbilling appears as a current asset, essentially an accounts receivable for work performed but not yet billed. In cash flow terms, underbilling is unfavorable because you have spent money to perform work but have not yet been reimbursed.
Chronic underbilling is a red flag for sureties and lenders. It suggests either poor billing discipline (you are doing the work but not sending invoices) or scope creep (you are performing work outside the contract without securing change orders). Either way, it means your cash flow is weaker than it should be.
Building Your First WIP Schedule
Column by Column
A standard WIP schedule includes the following columns for each active job:
Job name and number. Self-explanatory, but use the same naming convention across all reports for consistency.
Original contract value. The contract price at the time of execution, before any change orders.
Approved change orders. The total value of all approved (signed) change orders to date.
Revised contract value. Original contract value plus approved change orders.
Original estimated cost. Your bid estimate for total job cost at the time of contract execution.
Revised estimated cost. Your current best estimate of total job cost, reflecting all known changes, overruns, and adjustments.
Estimated gross profit. Revised contract value minus revised estimated cost.
Estimated gross profit percentage. Estimated gross profit divided by revised contract value.
Costs incurred to date. The sum of all job costs posted to date (labor, materials, subcontractors, equipment, overhead allocations).
Percent complete. Costs incurred to date divided by revised estimated cost.
Earned revenue. Percent complete multiplied by revised contract value.
Total billings to date. The total amount billed to the owner, including the current period.
Over/(Under) billing. Earned revenue minus total billings. A negative number means overbilled; a positive number means underbilled.
Getting the Inputs Right
The accuracy of your WIP schedule depends entirely on the accuracy of your job costing. Every cost associated with a project must be coded to the correct job number and cost category. This sounds obvious, but in practice, it is the most common failure point.
Materials purchased for Job A that get used on Job B distort both jobs' completion percentages. Subcontractor invoices that sit in accounts payable for weeks before being posted to the job understate costs incurred. Overhead allocations that are inconsistent from month to month create noise in the data.
Build a weekly job cost review into your project management process. Project managers should review their job cost detail every week, flag miscoded transactions, and confirm that all costs are captured before the monthly WIP is prepared.
Why Sureties Care About Your WIP
When a surety company evaluates your bonding capacity, they are assessing two things: your financial strength (do you have the net worth and liquidity to absorb project risk?) and your project management capability (can you actually execute the work profitably?).
The WIP schedule is the primary tool for evaluating project management capability. A well-prepared WIP tells the surety several things:
Estimating accuracy. By comparing original estimates to revised estimates across your jobs (a process called fade analysis), the surety can determine whether your estimating department is reliable. If every job's cost estimate increases after contract execution, your estimator is consistently low, which means your reported profits are probably overstated.
Billing discipline. A healthy mix of moderate overbilling and minimal underbilling tells the surety that you are managing your billing process effectively and maintaining strong cash flow.
Job diversity. The WIP shows your backlog concentration. If one job represents 60% of your total backlog, the surety will worry about the impact of a problem on that single project.
Completion trajectory. Jobs that show increasing costs without proportional billing progress may be heading toward losses. Sureties look for these patterns as early warning signs.
Common WIP Mistakes
Not updating estimated costs. This is the most damaging mistake. A WIP built on original estimates for jobs that are six months in is fiction. Require monthly estimate updates and hold project managers accountable for their accuracy.
Ignoring pending change orders. If you have submitted a change order but it has not been approved, it should not be included in your revised contract value. However, the costs associated with that work should be included in your costs incurred. This creates a temporary underbilling that resolves when the change order is approved.
Including retainage in billings. Your billings to date should represent the full amount billed, but your cash flow analysis must account for the fact that 5% to 10% of those billings are being held as retainage and will not be collected until project completion.
Lumping overhead costs. If you allocate overhead to jobs, use a consistent methodology (such as a percentage of direct costs) and apply it every month. Inconsistent overhead allocation makes job-to-job comparisons unreliable.
Preparing the WIP quarterly instead of monthly. A WIP schedule is only useful if it is current. Quarterly preparation means you are operating blind for two out of every three months. Monthly preparation, ideally completed within 10 days of month-end, should be non-negotiable.
From WIP to Financial Statements
Your WIP schedule directly feeds your financial statements. The net overbilling or underbilling across all jobs appears on your balance sheet as a current liability or current asset, respectively. The earned revenue on your WIP becomes the revenue on your income statement under the percentage-of-completion method.
If your financial statements are prepared on a completed-contract basis (recognizing all revenue and profit when the job is complete), the WIP schedule still matters for management reporting and surety analysis. Most sureties prefer to see financial statements on a percentage-of-completion basis because it provides a more timely picture of profitability. If your CPA prepares your annual statements on completed contract, consider producing internal WIP-based financials for surety and bank submissions.
The transition from understanding your WIP schedule to using it as a management tool is the difference between contractors who grow and contractors who plateau. Make it a monthly discipline, and it will become the foundation of every financial decision in your business.