BOQ, Actual, and Overrun Logic
BOQ value is usually a baseline budget signal, not leakage by itself. Actual cost is the evidence of what has been spent or incurred. A construction cost overrun should be calculated as Actual - Budget only when both values are available and comparable for the same scope. If Actual is greater than Budget, the result can be reviewed as overrun; it becomes leakage only when separate evidence supports a leakage category.
Practical checklist
- Confirm the BOQ item, budget line, or approved scope being compared.
- Collect Actual cost evidence such as invoice, payment certificate, purchase order, or cost ledger entry.
- Check that Budget and Actual refer to the same activity, item, package, period, or scope.
- Calculate overrun only when both values are available: Actual - Budget.
- Classify BOQ, planned spend, cumulative work done, and advance recovery as baseline signals unless separate evidence shows leakage.
- Escalate leakage only when evidence shows penalty, wastage, rework, delay cost, idle resources, delayed PO impact, excess consumption, or calculated overrun.
Example table
| Record type | Category | How to read it |
|---|---|---|
| BOQ item value | BASELINE_BUDGET | Approved or planned cost basis for comparison. |
| Actual invoice value | Evidence input | Used only when matched to the same BOQ item or scope. |
| Actual greater than Budget | Calculated overrun | Difference equals Actual - Budget when both values are present. |
| Rework invoice with site instruction | LEAKAGE_AND_OVERRUN | Leakage candidate if the source evidence supports the rework link. |
Internal links
For the service page, see construction cost leakage audit. For required records, read documents needed for a cost leakage audit. For schedule effects, see schedule delay cost impact.