Job costing for contractors: how to see which jobs made money
A healthy-looking P&L can hide a job that lost money, because the total nets out against a job that did well. Job costing is the only way to separate the two, and it is not a software feature so much as a habit at the point of entry.
The short answer
Job costing means tracking income and direct cost, labor, materials, subs, and equipment, against each individual job instead of letting it all land in one company-wide bucket. It answers a different question than your monthly P&L does: not whether the business made money this month, but which job actually earned its keep.
One number worth holding onto: retainage on a typical construction contract runs 5 to 10 percent of each progress payment, held back until the job closes out. If that holdback is not tracked against the job that earned it, the job looks weaker than it is until the money finally lands.
How job costing quietly breaks down
Cost coded to a category, not a job
Materials and subs get coded to an expense account so the P&L looks right, but nothing ties that line back to the job it belongs to.
Crew time split by guess
Payroll gets allocated across jobs after the fact, from memory, instead of tracked as the hours are worked.
Overhead absorbing job cost
Equipment, fuel, and small tools bought for one job get buried in a general overhead account instead of following the job.
Retainage disappearing from the number
The held-back percentage drops out of the job's numbers instead of sitting there as money already earned.
Change orders untracked
Scope and price change mid-job, but the original estimate never gets updated, so the job's actual margin is invisible.
Price used as a stand-in for margin
A big contract price feels like a win even when the cost behind it quietly outran the bid.
How we set it up
In QuickBooks Online, every job cost line, labor, materials, subs, equipment, gets tagged to a customer or project, not just coded to an expense account. That tag is what lets a report roll cost up by job instead of only by account. Retainage sits on the books as a receivable against that specific job, not as a gap that disappears from the numbers. We wrote more about how the pieces fit together, including retainage and progress billing, on our contractor bookkeeping cost guide.
What we actually do, and what we do not
We keep clean, CPA-reviewed books that tag cost to the job so you can see which jobs paid off, which is what most owners actually need. We do not build a dedicated project-cost accounting system the way a project office would. If your operation needs that level of detail, we will say so honestly on the contractor bookkeeping page rather than take on work we cannot do well.
Answers before you ask.
What is job costing, exactly?
Job costing means tracking the income and the direct cost of each job separately, labor, materials, subs, and equipment time, instead of letting everything land in one company-wide total. It answers a different question than your P&L does: not did the business make money this month, but did this specific job make money.
Why does my P&L already look fine if job costing is broken?
A P&L can show a healthy month even when one job lost money and another covered for it, because the total nets out. Without cost tracked at the job level, a job that quietly ate its margin looks identical, from the P&L alone, to a job that hit its number.
How do you actually set up job costing in QuickBooks Online?
Every job cost line, labor, materials, subs, equipment, gets tagged to a customer or project in QuickBooks Online, not just coded to an expense category. That tag is what lets a report roll cost up by job instead of only by account. It takes discipline at the point of entry more than it takes software.
How does retainage affect job costing?
Retainage, commonly 5 to 10 percent of each progress payment, is money already earned on a job that has not been collected yet. If it is not tracked as a receivable against that specific job, the job looks less profitable than it is until the holdback finally lands.
Do you build job costing systems for contractors?
We keep clean, CPA-reviewed books that tag cost to the job so you can see which jobs paid off, which covers what most owners need. We do not build a dedicated project-cost accounting system the way a project office would, and we will say so directly if that is what your operation actually needs.
Ready when you are
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