Valuing variations without breaking the payment cycle

Every project changes. On a Singapore contract the variation is the mechanism that turns a change in the works into money, and once valued it flows into the payment claim alongside the measured work. The discipline is in the valuation basis and in the instruction that authorised the work.

Value on the contract, in order

Standard forms such as the PSSCOC and the SIA conditions set out how variations are priced, and the order is familiar to any quantity surveyor.

• Contract rates, where the varied work is the same character and condition as work already priced in the contract.
• Rates derived from the contract, adjusted for a change in quantity or condition, where the work is similar but not identical.
• Fair valuation, where there is no comparable rate, built up from cost, plant, labour and a reasonable addition.

Instruction first, then price

The value only becomes claimable once the change has been properly instructed under the contract. Work done on a verbal nod, without the instruction the form requires, is the hardest money to recover, because the respondent can dispute both that it was ordered and what it was worth. Get the instruction in writing, then value it.

Into the payment claim

An agreed variation is not a separate invoice. It joins the cumulative gross valuation and is claimed through the ordinary payment claim under the SOP Act. That matters for two reasons. It keeps one running total rather than a scatter of side claims, and it means the variation is subject to the same response window and the same due date as the rest of the cycle.

Where a variation is instructed but not yet agreed in value, claim your reasoned assessment rather than leaving it out. Leaving it out delays cash and weakens the record. Claiming a defensible figure puts the onus on the respondent to answer it in the payment response.

GST follows the value

The variation is valued net. GST at nine per cent is added on the tax invoice with the rest of the certified sum, not built into the rate. Keep the net variation value clean, because that is the figure the SOP Act and any later adjudication will work from.

Price it on the contract, instruct it before it is built, and carry it into the running claim. A variation handled that way is just more valued work. One handled loosely becomes a dispute that outlives the project.