Job Costing for Construction: How to Track Every Dollar by Project

What Is Job Costing and Why Does It Matter?

Job costing is a method of accounting that assigns every expense to a specific project. In construction, this means every dollar of labor, materials, subcontractor payments, equipment rental, and overhead is tracked to the job it belongs to — and often to a specific phase within that job (foundation, framing, electrical, plumbing, finish).

Without job costing, you're flying blind. Your overall P&L might show 20% gross margin, but if three of your five active jobs are losing money and two are carrying the weight, you won't know until it's too late. Job costing turns your books from a rearview mirror into a windshield.

How Construction Job Costing Works in QuickBooks

Step 1: Set Up the NAHB Chart of Accounts

The NAHB Chart of Accounts is the construction industry standard. It separates direct costs (materials, labor, subs) from indirect costs (overhead, G&A) and breaks direct costs into phases. This structure is what banks, bonding companies, and CPAs expect to see from construction companies.

Step 2: Create Projects in QuickBooks

Every active job gets its own project in QBO. Each project tracks its budget (from your estimate), actual costs (from invoices and time entries), and revenue (from progress billing). The delta between budget and actual is your job cost variance — the number that tells you if you're making or losing money.

Step 3: Map Cost Codes to Your PM Software

If you use Buildertrend, Procore, or Knowify, your cost codes should map directly to your QuickBooks chart of accounts. This eliminates double entry — data entered in the field flows automatically to your books. Without this mapping, your PM software says one thing and QuickBooks says another.

Step 4: Weekly Estimates vs. Actuals Review

Every Friday, run an Estimates vs. Actuals report for every active project. This 30-minute review catches cost overruns, unbilled change orders, and labor inefficiencies before they compound. The contractors who do this consistently are the ones who hit their margins.

Common Job Costing Mistakes Contractors Make

Dumping Everything into "Materials"

If all your material purchases go into one category, you can't tell if framing lumber, plumbing fixtures, or electrical supplies are driving cost overruns. Break materials into categories that match your estimate structure.

Not Tracking Labor by Job

If your crews work multiple jobs in a week but all labor goes to one general "wages" account, you have no idea which project is eating your labor budget. Use time tracking (QuickBooks Time, Buildertrend, or field apps) to allocate hours to specific jobs and phases.

Ignoring Change Orders

Approved change orders that don't get invoiced are the #1 profit leak in construction. The work gets done, the cost hits your books, but the revenue never comes in. Our average client recovers $28,400 in unbilled change orders in the first 60 days of working with us.

Waiting Until the Job Is Done

If you only look at job costs after a project is complete, you've lost the ability to fix anything. Weekly reviews catch problems while there's still time to adjust — renegotiate with subs, tighten material ordering, or bill for approved extras.