What is job costing in construction?
Job costing is the practice of tracking all the costs of a specific project, labor, materials, equipment, and subcontractors, against that job's budget. It tells you which jobs are making money and which are bleeding margin, ideally while you can still do something about it rather than at closeout.
Budget vs actual, by cost type
Good job costing compares budgeted to actual cost for each category and includes committed costs (signed but not yet invoiced) so you see where a job is heading, not just where it has been. Catching an over-budget bucket mid-job protects the margin you bid.
Why real-time beats month-end
If job costs only update when the books are reconciled at month end, you learn about a losing job weeks too late. Keeping costs current, as bills come in, turns job costing from a post-mortem into an early-warning system.