WIP stands for Work in Progress, and WIP reporting is a method contractors use to recognize revenue and costs on projects that span multiple accounting periods. Instead of booking all revenue when a project finishes or when invoices go out, WIP matches revenue recognition to the actual work completed.

The core idea is percentage of completion. If you’ve spent 40% of the estimated costs on a project, you recognize 40% of the expected revenue. This gives a more accurate picture of how the business is actually performing, rather than having financial statements swing wildly based on billing cycles.

For each open project, you need three numbers: contract amount, total estimated costs, and costs incurred to date. The math is straightforward. Divide costs incurred by total estimated costs to get your completion percentage. Multiply that by the contract amount to get earned revenue. Compare earned revenue to what you’ve actually billed.

If you’ve billed more than you’ve earned, that’s overbilling. The difference shows as a liability on your balance sheet because you owe that work to the customer. If you’ve billed less than you’ve earned, that’s underbilling. The difference shows as an asset because the customer owes you for work already performed.

These adjustments matter because without them, your financial statements don’t reflect reality. A contractor could look profitable just because they sent out front-loaded invoices, or look broke because they’re working on a big project they haven’t billed yet. Banks and bonding companies know this, which is why they require WIP schedules.

Bonding companies in particular care deeply about WIP. They’re guaranteeing your ability to complete work, so they want to know if you’re consistently overbilling or underbilling. A pattern of heavy overbilling suggests you’re spending customer money before earning it. Heavy underbilling could indicate cash flow problems or scope creep eating your margins. Either pattern can limit your bonding capacity.

The challenge is that WIP requires accurate construction job costing as the foundation. If you don’t track costs by project reliably, or if your estimates aren’t realistic, the WIP numbers are meaningless. Getting good job cost data is the hard part. The WIP calculation itself is mechanical once you have clean inputs.

Most contractors running projects over $500K or needing performance bonds will encounter WIP requirements. Even if nobody’s requiring it, WIP reporting helps you understand which projects are making money and which are slipping. A project can look fine based on billing but be underwater when you compare earned revenue to costs incurred.

If you’re a San Diego contractor who needs WIP reporting for bonding or banking purposes, working with a San Diego bookkeeper who understands construction accounting makes a real difference. WIP isn’t complicated once the underlying job costing is solid, but getting to that point takes discipline and proper systems.