Cap. 22:23 Puauc PROCUREMENT AND DISPOSAL OF Pusuc AssETS No.S/2017 the variation would result in a contract materially different from the original contract or would significantly alter the nature or scope of the contract. (3) Where a procuring entity wishes to vary a procurement contract(a) in a manner referred to in subsection (2); or (b) so as to increase the contract price to a greater extent than is prescribed or permitted by section 80 ("Approaches to pricing in procurement contract"); the procuring entity shall either initiate fresh procurement proceedings or, where appropriate, embark on direct procurement in terms of section 33. 82 Payment under procurement contract ( 1) Payments under a procurement contract shall be made within the time-limits set out in the contract, and the contract may provide for the payment of compensation for a failure to make the payments within those time-limits. (2) A procurement contract may provide for the procuring entity to make progress payments based on progress in the fulfilment of the contract, and such payments maybe(a) calculated as a percentage of the total performance due under the contract; or (b) paid according to the achievement of performance milestones identified in the contract; or (c) based on actual quantities delivered or completed; or (d) paid or calculated on any other basis that may be prescribed. (3) Progress payments shall not be made except upon presentation and acceptance of such documentation as is required under the procurement contract as evidence of the progress in performance. · (4) Where a procurement contract provides for the making of progress payments, the contract may provide that the procuring entity may withhold a percentage of the amounts due as retention money until performance of the procurement contract is completed. (5) When necessary to enable effective implementation of the contract, a procurement contract may provide for the procuring entity to make advance payments of the price: Provided that(i) the total amount of advance payment made under the procurement contract shall not exceed the prescribed percentage of the total contract price; (ii) unless otherwise stipulated in the contract, an advance payment shall not be made unless the contractor furnishes an advance payment guarantee covering the amount of the advance payment and satisfies any other terms set out in the bidding documents. (6) Where a procuring entity bas made an advance payment under a procurement contract(a) the contractor, and any of its subcontractors, shall utilise materials, equipment and personnel that are the subject of the advance payment only for the work or services for which the advance payment was made; (b) in the case of a contract for the construction of works, the contractor and any subcontractors shall commit the materials, equipment and personnel that are the subject of the advance payment exclusively to sites related to the works covered by the contract and for which the advance payment was made. 89