What the review should establish
A BOQ-to-actual review should establish whether two genuinely comparable values exist for the same scope, quantity basis, period, location, and revision. The approved BOQ or control budget provides a baseline; certified work, invoices, cost ledger entries, material consumption, and approved commitments provide different views of actual or forecast cost. These values should not be mixed without explaining their basis.
Cost overrun is the positive difference between comparable actual cost and budget. It is not automatically leakage. Approved scope growth, instructed variations, market movement, design development, delayed decisions, rework, wastage, low productivity, or coding errors can create different variance types and different commercial responses.
Prepare a like-for-like comparison
- Identify the approved BOQ, budget, or change-control revision and its approval date.
- Map BOQ items and cost codes so that description changes do not conceal duplicate or misplaced cost.
- Separate original scope, approved change, pending change, and unauthorized work.
- Use a consistent cut-off date and distinguish incurred cost, certified value, paid amount, commitments, accruals, and forecast-to-complete.
- Normalize units, quantities, taxes, retention, advances, recoveries, and exclusions before comparing rates or totals.
- Record the source reference for every material input and mark unsupported values as missing evidence.
Read each variance before classifying it
| Variance | Question | Evidence to examine |
|---|---|---|
| Quantity | Was more work executed, measured, or paid than the baseline allowed? | Drawings, measurement books, bills, quantity reconciliation, and changes. |
| Rate | Did the effective purchase or subcontract rate exceed the approved basis? | Rate analysis, quotations, PO, invoice, escalation terms, and approvals. |
| Scope | Is the cost new approved work, omitted baseline scope, or unauthorized work? | Instructions, drawings, variation register, approvals, and correspondence. |
| Execution | Does the difference arise from rework, waste, delay, idle resources, or productivity? | Site reports, NCRs, material logs, resource records, programme, and notices. |
Review sequence
- Lock the baseline revision and reporting cut-off; document both visibly.
- Build a crosswalk between BOQ items, work packages, purchase orders, invoices, and ledger cost codes.
- Reconcile quantities first, then rates, then total value. This prevents a total variance from hiding its cause.
- Separate actual cost from committed and forecast cost, while showing all three in the control view.
- Calculate variance only where scope and basis align; preserve the calculation and source references.
- Test significant differences against approved changes, site events, material movement, and payment records.
- Classify the result as explained variance, supported exception, calculated overrun, or missing evidence.
Decision-ready output
A decision-ready variance schedule should show the BOQ or budget baseline, approved changes, current budget, actual-to-date, commitments, forecast-to-complete, variance, cause, evidence references, confidence, owner, and proposed action. The action may be budget correction, change approval, cost recovery, procurement intervention, further substantiation, or no action where the variance is properly explained.
Report arithmetic separately from judgment. A calculation can show that actual exceeds budget; only linked project evidence can explain why and whether the difference is recoverable, avoidable, contractual, or simply a control-data issue.
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.