Provisional sums, price adjustment and Employer-supplied items: three tender concepts that should never be mixed

A provisional sum is not a general contingency for the contractor. It is an allowance identified in the contract for specified work, goods or services to be instructed and valued under the contractual mechanism. The bidder should understand whether overhead and profit are added, what attendance is included, how nominated or instructed work is valued and whether unused provisional sums disappear from the contract price.

Price adjustment addresses a different risk: changes in input cost over time. The tender team should test the formula, indices, currencies, base date, weightings, non-adjustable portion, thresholds and whether major imported materials are represented by appropriate indices. A price-adjustment clause can still leave significant unhedged exposure if the formula does not match the real cost structure.

Employer-supplied materials or equipment create interface and delay risk rather than simple price relief. The contractor may avoid purchase cost but still need unloading, storage, preservation, inspection, installation, testing, integration and responsibility after receipt. The contract should define delivery point, date, condition, quantity, spare parts, documentation, risk transfer and relief if the Employer delivers late or defective items.

These three mechanisms should therefore be modelled separately in the bid: provisional-sum scope risk, escalation/index risk and Employer-supplied interface risk. Combining them in a single generic contingency hides the commercial logic and makes post-award control difficult.

This article is engineering and tender-risk guidance. The signed bidding documents, conditions of contract, technical specifications, drawings, bill of quantities, method of measurement and applicable law govern each project. Contractual and legal interpretations should be confirmed by qualified advisers where material.