You bid the job at a solid markup. Then the change order came in and never got billed, the job took a week longer than planned and then the customer had issues that needed to be addressed. None of that shows up on the invoice you sent. It shows up in what’s left when the job is done, and by then it’s too late to catch it.
Markup tells you what you planned to make. Job costing tells you what the job cost, materials, labor, every trip and every change, measured against what you billed for it. That’s the only way to see where a job you called profitable lost money along the way.
This week, pull one job that’s already closed and run the real numbers against the bid. Actual materials, actual hours, actual costs. See where the gap opened up.