Can a payment certificate be revised?

Contractors rely on interim payment certificates to provide the essential cash-flow for their projects. A contract would ordinarily stipulate the interval in which progress claims are made, certificates are issued, and payments made on those certificates.

The PAM Form stipulates that a payment certificate shall be “the total value of the work properly executed and include the percentage of the value of materials and goods stated in the Appendix up to the date of the Contractor’s payment application less any amount which may be retained…The materials and goods must be for incorporation into the permanent works and have been delivered to and properly stored at the Site and be protected against loss, damage or deterioration and be in accordance with the Contract. The certificate shall only include the value of materials and goods which are reasonably, properly and not prematurely brought to the Site”.

The Quantity Surveyor would ordinarily value the works and value of materials on site. It must be borne in mind that the valuation should only take into account works “properly executed”- therefore if works are incomplete or improperly executed, they may be excluded from valuation or a diminished value be allocated for the same.

In a perfect world, the interim valuations would capture perfectly the progress of works and delivery of materials to site. However, the reality is always less than perfect.

Therefore, there may be situations where claims are made for works purportedly done, which are not yet done, but it was valued anyway due to a lack of proper checking. Some works may have been completed but improperly (for example items may be installed which do not meet specifications), and these would be valued as well. Materials at site may not be adequately protected, leading to deterioration subsequently but already valued and paid.

Can these interim certificates therefore be revised?

Yes, and No.

No, an interim certificate cannot be revised save for “clerical, computational or typographical error or errors of a similar nature” In other words, once a decision with regard to the valuation of interim certificates is made, that decision cannot be revised willy-nilly.

However, “the Architect may, by a later certificate, make correction or modification in respect of any valuation errors in any earlier certificate”. Therefore, at any time before the final account is concluded, the Architect can adjust subsequent certificates to correct or modify earlier certificates, including to issue negative certificates if necessary.

The only exception would be the Final Certificate, which would be conclusive once issued in so far as it relates to the final value of the works. However, even the Final Certificate would not be conclusive that works, materials and goods are in accordance with the Contract.

Kheng Hoe Advocates advises clients on CIPAA, arbitration, litigation and mediation of construction disputes. We can be reached at

The danger of under-pricing quantities

Sometimes, in an attempt to procure a contract, contractors under-price certain items in the Tender BQ. This could have been done perhaps because the contractor estimated that the said items would be of minimal cost or the cost for the same could be easily absorbed.

A problem arises when there is a variation involving the same items in the BQ which had been under-priced. In the case of Dudley Corporation v Parsons & Morris Ltd, a contractor under-priced the task of excavating rock, whereby he priced the task at £75 per 750 cubic yards. He did so because at the stage of tender, it was not certain that there would be any rock encountered.

A problem arose during the execution of the contract whereby a total of 2,230 cubic yards of rock were encountered and had to be excavated. It was accepted by the contractor that for the first 750 cubic yards, the cost would be £75. However, what about the excess? The quotation by the contractor was a gross under-estimate.

The architect took the view that for the excess rock encountered, the contractor ought to be allowed a reasonable rate of £2 a cube. The employer was not pleased with the architect’s decision and challenged the same.

The Court of Appeal held that the issue was a matter of contractual interpretation, and that “the actual financial result should not affect one’s view of the construction of the words”. In other words, the contractor was bound to honour the quote of £75 per 750 cubic yards even for the excess quantities.

This should serve as a caution to contractors, against the practice of under-quoting for certain items in the BQ in order to lower the overall pricing for purposes of securing the contract. Such under-quoting of certain items may well be a major disadvantage in the event there is any variation which substantially increases the said items.

Kheng Hoe Advocates advices clients on CIPAA, arbitration and litigation of construction disputes. We can be reached at