By S&S Co. Advocates & Solicitors · Published 19 February 2026 · Informational content, not legal advice
About this article: A general explainer prepared by S&S Co. Advocates & Solicitors on a recurring type of dispute. It does not report a specific judgment or order, names no parties and gives no case citation, so it should not be cited as authority. Law and practice change; please verify against the current statute and primary sources before relying on it.
Under EPC and construction contracts, an engineer or employer's representative issues interim payment certificates that set the amount payable to the contractor at each stage. Contractors often argue that a certified sum is payable and cannot be reopened. Employers often argue that work found defective after certification can be corrected in a later certificate.
In contracts modelled on FIDIC-style conditions, an interim certificate is generally provisional. It can be corrected or modified in a later certificate or at the final account, unless the contract says that interim certificates are final and binding. The wording of the payment and certification clauses therefore decides whether the employer may raise defect-based deductions against a certified amount.
Even where a certificate is open to challenge, a court or tribunal may order payment of the part of the certified sum that is not genuinely disputed, and leave the disputed part to be decided. A bona fide dispute over some items is not usually a reason to withhold the whole amount.
Key Points
- An interim certificate is generally provisional under FIDIC-style conditions, unless the contract says it is final and binding.
- Defect-based deductions can usually be raised against a certified sum, but undisputed amounts are often ordered to be paid.
- The certification clause and the notice requirements decide most disputes of this kind.