Job costing tracks costs — what has been spent and committed on the project versus the budget. Billing tracks revenue — what the contractor has invoiced the client versus the contract value. On a fixed-price contract, billing is based on a schedule of values (percentage-complete billing at milestones) — the contractor invoices 30% of the contract value when framing is complete, regardless of actual framing cost. Job costing tracks whether the actual framing cost was more or less than the estimated cost. The gap between billing and costs is the project margin. Billing should run slightly ahead of costs to maintain positive contractor cash flow; billing significantly ahead of work completed (overbilling) is a client protection issue. RainFire Builders maintains both job cost and billing tracking and provides both in monthly reporting on larger projects.