THE BILLING PROBLEM Job costing is simple until you hit the billing. Six ways billing shows up on a construction job,. 1) Fixed price, paid upfront One deposit, one job, no milestones. Only real job track actual costs against the flat price so you know your real margin. 2) Time & material, bill at completion Track labor hours and material costs as the job runs. One invoice at the end matching costs to that single invoice is the only work. 3) Progress billing, no retainage Milestone invoices as phases complete. Clean split between billed to date and costs to date. No retainage to hold. 4) Progress billing retainage Now you're running AIA G702/G703s. Retainage held back on every draw you need a WIP report or the real profit stays invisible. 5) Multi trade job, shared overhead Several subs, one job, shared equipment and overhead to allocate. WIP has to break out by job, not just by invoice. 6) GC billing owner , paying subs, retainage both ways You are billing the owner AND holding retainage on your subs at the same time. Full WIP schedule, over or under billing, retainage receivable and payable one wrong entry and your job profitability report lies to you. Biggest point don't skip WIP reporting the moment you cross into progress billing. This is exactly where contractors get blindsided the bank account looks fine and the job is quietly losing money. Let me know what you think of this.