The Job That Lost You Money (and Why You Don't Know Which One It Was)

Ask most contractors how business is going and you'll hear about revenue: "we billed $80k last month." Ask which jobs made money and the answer gets fuzzy. Materials went on the card, labor got paid weekly, the dump fees and fuel and small-tool runs disappeared into the pile - and at the end of the year, the tax return shows a profit number nobody can trace back to actual work.

That's the gap job costing closes. It's the single highest-value bookkeeping habit for a trades business.

What job costing actually means

Job costing is tagging every dollar of income and expense to the job it belongs to. Not just the big invoice - the materials receipts, the sub payments, the equipment rental, the labor hours. When it's set up right in QuickBooks Online, every project shows its own mini profit-and-loss:

• Bid price vs. what you actually spent - while the job is still running, not six months later
• Margin by job type - maybe your bathroom remodels run 38% gross margin while your deck builds run 12%. That changes what you bid on next spring.
• Margin by customer - the builder who always adds "one more thing" shows up in the numbers, not just your patience
• Where overruns live - materials creep, labor overruns, or underbidding, each has a different fix

Why "I'll sort it out at tax time" costs real money

Year-end catch-up bookkeeping answers one question: what does the IRS need? It can't answer the questions that make you money, because by then the information is gone - nobody remembers in February which Home Depot run belonged to which job from last May.

Monthly bookkeeping with job costing means:

• You reprice while it matters. If material costs jumped 15% mid-season, your next bid reflects it.
• Progress billing doesn't slip. Jobs tagged and tracked means unbilled work surfaces every month.
• Sales tax stays clean. Job-level records are also where capital improvement vs. repair treatment lives - the two systems reinforce each other.
• Tax planning becomes possible. Quarterly numbers you trust mean estimated payments based on reality, not guesswork - no April surprise.

The setup that works in QuickBooks Online

For most Capital Region trades businesses we set up:

• Projects (QuickBooks' job-costing feature) for every job over a size threshold
• A chart of accounts built for trades - materials, subcontractors, equipment, permits and fees broken out, not lumped into "supplies"
• Bank feed rules that route recurring vendors to the right categories automatically
• A monthly close - reconciled accounts, categorized transactions, and a P&L by job in your inbox

Once it's running, the owner's time cost is close to zero - snap receipts, answer a couple of categorization questions a month, read the report.

FAQ

Do I need QuickBooks Desktop Contractor Edition for real job costing?

No - QuickBooks Online's Projects feature handles job costing well for most small trades businesses, and it's where the ecosystem is heading.

Is job costing worth it for small jobs?

Set a threshold. Tagging every $300 service call individually may not pay; tagging everything over a few thousand dollars almost always does.

Can you fix last year's books so I can see job margins?

Catch-up cleanups can usually reconstruct the big picture, but receipts-to-jobs detail degrades fast. The real answer is to start clean going forward - that's a two-week setup, not a year-long project.