Every July I sit down with a contractor who is having a great year on paper. The P&L shows $250,000 of profit through June. Then we build a WIP schedule and half of it evaporates. Nobody stole anything. The books just measured the wrong thing.

Here is the problem in one sentence: your P&L records revenue when you bill, but you earn revenue as you build. On a two week service call those are basically the same. On a nine month custom home in Encinitas they can be $100,000 apart.

What a WIP schedule actually is

A work in progress schedule is a one page report listing every open job with five numbers: contract price, estimated total cost, cost to date, percent complete, and billed to date. From those, it calculates what you have truly earned on each job and compares it to what you have invoiced.

Percent complete comes from cost, not gut feel. If a job will cost $600,000 to build and you have spent $300,000, you are 50 percent complete. On an $800,000 contract, that means you have earned $400,000 of revenue. Full stop. It does not matter whether you have billed $300,000 or $500,000. The billing is just paperwork. The earning is the truth.

Overbilling: the profit that is not yours yet

Say that $800,000 remodel is 50 percent complete, so you have earned $400,000. But your payment schedule was front loaded and you have billed $480,000. You are overbilled by $80,000.

Overbilling is not illegal and it is not even bad. Front loading your billings is smart cash flow management, and I encourage it. The danger is forgetting what that $80,000 is. It is not profit. It is your customer prepaying for work you still owe them. On a real balance sheet it shows up as a liability called billings in excess of costs. If you spend it on a new truck in August, you will be paying October’s framing crew out of your own pocket.

This is the classic contractor cash trap: a fat bank account in the middle of the job and a painful squeeze at the end. The WIP schedule is the only report that warns you.

Underbilling: you have become the bank

Now flip it. A Carlsbad GC I will call Mike had a $450,000 commercial TI that was 60 percent complete. He had earned $270,000 but only billed $210,000 because change orders were sitting unsigned and his June invoice went out late. He was underbilled by $60,000.

That $60,000 was money Mike had already spent on labor and materials without invoicing anyone for it. He was financing his customer’s project interest free while paying 9 percent on his own line of credit. Chronic underbilling is also the first place profit fade hides: sometimes a job is not really underbilled, the cost estimate is just wrong and the profit was never there.

What a simple WIP schedule looks like

Here is a stripped down two job example. Yours might have ten jobs, but the math never changes.

Earned = contract price × percent complete. Percent complete = cost to date ÷ estimated total cost.

Why the fade shows up in Q4

Profit fade is when a job that looked like an 18 percent margin in March finishes at 9 percent in November. It almost never happens all at once. It leaks: a $12,000 concrete overage here, three unbilled change orders there, two extra weeks of supervision at $2,800 a week. A monthly WIP schedule catches the leak in month two, when you can still fix pricing on the next bid or chase the change order signature. An annual review catches it at the company Christmas party, when all you can do is wince.

Bankers and bonding agents read this first

If you ever want a bigger line of credit or bonding capacity beyond small jobs, know this: the WIP schedule is the first page your surety and your banker turn to. A contractor who shows up with a clean monthly WIP schedule reads as someone who knows where every dollar is. A contractor who cannot produce one reads as risk, and risk gets priced into your rates or declined outright. I have watched bonding capacity double for the same company simply because the paperwork finally proved what the owner already knew.

How to start without drowning in spreadsheets

You do not need fancy software to begin. You need job costing that actually tags costs to jobs, current cost to complete estimates from whoever runs your projects, and one hour a month to put the five numbers side by side. Start with your three biggest open jobs. If the over and under column surprises you on any of them, that surprise just paid for the hour.