The Interim Payment Certificate, and the valuation underneath it
On a Doha project run under the FIDIC Red or Yellow Book there is no statutory payment scheme to lean on. The IPC is the whole mechanism, and it is only as good as the measure behind it.
QScope Team · 2 March 2026 · 6 min read
Qatar has no Security of Payment Act. On the large infrastructure and building work that followed the World Cup legacy programme, the payment machinery is whatever the contract says, and on most jobs that contract is the FIDIC Red or Yellow Book. The Interim Payment Certificate is the engine, so it repays understanding it properly.
Statement first, certificate second
The Contractor does not invoice in the ordinary sense. Under Sub-Clause 14.3 the Contractor submits a Statement showing the amounts considered due, supported by the measure and the documents. That Statement is the trigger. Nothing runs until it is with the Engineer.
The Engineer then has twenty-eight days from receipt of the Statement to issue the IPC under Sub-Clause 14.6, certifying the amount that is properly payable. The certificate can be for less than the Statement claimed, and frequently is. What the Engineer certifies is the sum that becomes due.
What the IPC actually values
The certified sum is the value of work properly executed to the valuation date, plus materials and Plant where the contract allows, plus any Variations valued under Clause 13, less retention, less amounts previously certified, less any deductions the contract permits. It is a running gross figure with the previous certificate netted off, not a fresh invoice each month.
- Measure to date. The permanent work in place, valued against the Bill or the Schedule, not against the programme or the Contractor optimism.
- Variations. Instructed changes valued under Clause 13, carried into the same certificate rather than parked for the final account.
- Retention. Deducted at the contract percentage under Sub-Clause 14.3, held until the two release points.
- Prior certificates. The gross-to-date figure less everything certified before, which is the number that governs the payment.
Why the underlying valuation carries the risk
Because there is no statutory backstop, an IPC that under-certifies is not cured by a smash-and-grab remedy the way it might be in a Construction Act jurisdiction. The Contractor route is the contractual claim, and eventually the dispute machinery. That makes the monthly measure the place where cash is won or lost, not the certificate wording.
A Statement built on a clean, current valuation gives the Engineer little room to trim. A Statement built on round numbers and a percentage guess invites the Engineer to certify conservatively, and the Contractor spends the next month arguing back the difference it should never have conceded.
The discipline that pays
Keep the measure current between valuation dates rather than assembling it the night before the Statement is due. Value Variations as they are instructed. Reconcile the gross-to-date figure every cycle so the netting off is arithmetic and not a source of dispute. On a FIDIC job the IPC is the only payment you get, and it is exactly as strong as the valuation you hand the Engineer.
QScope builds the interim valuation that sits under each Statement, so the figure the Engineer certifies in the IPC is one you can defend line by line.