Start by assigning every project a job number in your accounting software. QuickBooks and most construction accounting tools let you create jobs or projects. Each expense, labor hour, and subcontractor payment gets tagged to that job number. Without this basic structure, your books show total expenses but can’t tell you which projects actually made money.

Create cost codes that match how you estimate jobs. Most contractors break costs into labor, materials, subcontractors, equipment, and job-specific overhead. Within each category, you can get more specific if it’s useful. Materials might split into lumber, concrete, electrical supplies, and so on. The goal is a structure that lets you compare actual costs to your original estimate at a level detailed enough to act on.

Code expenses when they happen, not later. Buy supplies at the store and assign them to the job immediately or at least the same day. Wait two weeks and you won’t remember which project those materials went to. The same applies to subcontractor invoices and equipment rentals. If coding feels like a chore, you’re probably letting too much pile up.

Track labor hours by project. Your crew needs to record time spent on each job, ideally by cost category if they’re doing different types of work throughout the day. Guessing at labor allocation after the fact produces numbers that look right but aren’t useful. Time tracking apps or simple paper timesheets work as long as they’re filled out daily and assigned to specific jobs.

Compare budget to actual costs weekly during active projects. A monthly review means you discover framing ran 20% over after the house is already dried in. Weekly reviews catch problems while you can still adjust scope or push back on change orders. Many construction businesses struggle with profitability because they only look at job costs after the project is complete and the damage is done.

Committed costs trip up a lot of contractors. You’ve signed a contract with an electrician for $25,000 but only paid $8,000 so far. Your spent-to-date looks fine. Your real position is $25,000 committed against whatever you budgeted. Track commitments alongside actual spending to see the true picture.

The payoff from proper job cost tracking is knowing your real margins by project. You stop guessing at which jobs made money. You can see patterns in where you consistently underestimate costs. Your future bids get better because they’re based on actual data instead of assumptions.

If setting up job costing feels overwhelming, that’s common. Most contractors are great at building but don’t have time to configure accounting systems or train crews on proper tracking. A Detroit bookkeeping service that understands construction can set this up correctly and maintain it so you get useful numbers without doing the work yourself.