Job costing is the practice of recording every cost on a construction project against the specific job and cost code it belongs to, then comparing those costs with the job's budget so you know, line by line, whether the work is making or losing money.
UK readers: the closest equivalents are cost value reconciliation (CVR) and the discipline of tracking committed cost. The US term puts more weight on cost codes and cost types.
Most construction businesses don't lose money on the whole company at once. They lose it one job at a time, and inside each job, one scope at a time. Job costing is how you find out which one, early enough to do something about it.
Cost codes and cost types
Job costing works because every cost is tagged twice.
Cost codes describe what the money was spent on: the piece of scope. Many contractors base theirs on the CSI MasterFormat divisions (for example, Division 09 for finishes), then add their own detail underneath. A drywall contractor might have separate codes for metal framing, board, taping and finishing, and acoustic ceilings. The rule of thumb: detailed enough to see where a job is going wrong, simple enough that the field will actually code costs correctly.
Cost types describe what kind of cost it is. The usual set:
- Labor: field wages, and often the labor burden on top (payroll taxes, insurance and benefits), depending on how your accounting is set up.
- Material: everything purchased to be built into the job.
- Subcontract: work let to subcontractors.
- Equipment: owned or rented equipment, lifts, tools.
- Other: permits, dumpsters, temporary facilities and so on (some contractors code these as general conditions).
Tag a cost with both and you can answer questions like "how is subcontracted framing tracking against budget on this job?" in seconds instead of an afternoon.
Budget, committed, actual: the three numbers that matter
A job cost report earns its keep by putting three figures side by side for every cost code:
- Budget: what you estimated the work would cost when you won it, adjusted for approved change orders.
- Committed cost: money you have contractually agreed to spend, whether or not it has been invoiced: purchase orders, subcontracts, rental agreements.
- Actual cost: cost that has hit the books: posted invoices, payroll, expenses.
Most job cost reports focus on budget versus actual. The trouble is that actual cost is late. A subcontract signed today might not be invoiced for six weeks. If the subcontract is $10,000 over the budget line, the job is $10,000 worse off today, but a budget-versus-actual report won't show it until the invoice lands. That is why committed cost is the earliest honest signal a job gives you.
Estimate to complete and projected final cost
The other half of job costing is looking forward:
- Estimate to complete (ETC): what you still expect to spend on each cost code to finish the work.
- Projected cost at completion (also called estimate at completion): cost to date plus estimate to complete, or, using commitments, committed cost plus whatever is still uncommitted plus known risks.
- Projected variance: budget minus projected cost at completion. Negative means the line is forecast to overrun.
Projected final cost is also what drives percent complete on your WIP schedule. If it is too optimistic, the job looks more profitable than it is, right up until closeout.
Job costing example (illustrative)
Take one cost code on a commercial interiors job: metal framing and drywall. The numbers below are illustrative only.
The budget from the estimate is $85,000. The contractor has signed a subcontract with an installer for $78,000 and raised a purchase order for board and studs of $9,500. Invoices so far total $40,000. The superintendent also knows about $2,000 of extra patching labor that hasn't been ordered yet.
| Measure | Amount |
|---|---|
| Budget | $85,000 |
| Committed (sub + PO) | $87,500 |
| Actual to date | $40,000 |
| Projected at completion | $89,500 |
| Projected variance | ($4,500) |
Committed is $78,000 + $9,500 = $87,500. Projected cost at completion adds the known $2,000 of uncommitted cost: $89,500. Against a budget of $85,000, that is a $4,500 projected overrun.
Now look at what a budget-versus-actual report would have said: $40,000 spent against an $85,000 budget, so 47% of budget used and nothing to see. The overrun only shows up if commitments are in the report. With $4,500 visible today, the project manager can still challenge the material order, look for a change order the owner should be paying for, or adjust the forecast honestly.
Common job costing mistakes
- Coding to whatever is easiest. Field staff code everything to one general line because it's quicker. The report is accurate in total and useless in detail.
- Budgets that don't match the estimate. If the budget can't be traced to the estimate the job was won on, variances are noise.
- Commitments that live in a drawer. Purchase orders placed by phone, subcontracts papered late. Each one hides cost.
- Change orders that only hit one side. The owner change is added to revenue but the budget isn't updated, or the cost arrives with no matching change.
- Reviewing too late. A job cost report reviewed two weeks after month-end reports history. Weekly on big jobs is better.
How Vyntworks handles job costing
Vyntworks uses UK terms in the product, but the model is the same. When you win a job, the estimate becomes the project's budget, line by line, so there is no re-keying between the bid and the job. On the procurement side, purchase orders and subcontract orders are raised against those budget lines, with committed-versus-estimated tracked per line and sign-off routed by order value before anything is issued. You can see the whole flow on the platform overview.
On the cost control side, a live CVR sets budget, committed, actual and forecast side by side per project, and the overspend report lists every line where order spend has passed budget. Actual cost can come from matched invoices, or from the Xero ledger where it's connected. Live CVR, WIP and the overspend report are part of the Vyntworks Intelligence add-on; see pricing.
If your job cost report only tells you about overruns after the invoices arrive, book a walkthrough and we'll show you committed cost moving on a project shaped like yours.