ECOWAS Tenders Code b) Where the variation in the quantity of the works, supplies or services exceeds 10 percent but is less than or equal to twenty five percent (25%) of the basic contract value, such variation shall be the subject of an amendment to the contract. c) Where the totality of the variation in the quantity of the works, supplies or services exceeds twenty five percent (25%) of the contract value calculated on the basis of initial costing, a new contract shall be drawn up using the same procedure as for the initial contract. d) The total amount granted by virtue of amendments in respect of a single contract shall not exceed twenty five percent (25%) of the initial contract value. e) Price reviews in compliance with contractual terms shall not justify the introduction of amendments to the contract. 2. Additional clauses shall be drawn up and approved under same terms as the initial contract. 3. No additional clauses shall be added after final delivery of the goods and services. Chapter IV: Payments in Public Contracts Article 72: Advance Payments Progress and Final Payments Suppliers, contractors and service providers are entitled to advance payments and progress payments in accordance with the provisions set forth below. Each contract shall specify the administrative and technical conditions governing the payment of the advances or progress payments referred to in this chapter. Article 73: Advance Payments 1. Advance payments may be made under the contract. The total amount of these advance payments may not, in any case, exceed thirty (30) percent of the initial price of the contract for works, goods and services and intellectual services. 2. Advance payments and their terms of payment must be specified in the bidding documents or request for proposals. Whatever the amount is, they should be fully secured by a bank / insurance guarantee, or a joint and several guarantee. For intellectual services, this guarantee is not required if the advance payment is limited to a maximum of Ten (10) per cent of the total contract price. 3. Advance payments are reimbursed according to a fixed rate specified in the contract, by deduction from the sums due to the supplier, contractor or service provider, and in any event before the end of the contract. In the case of a total or partial termination of the contract, the procuring entity has the right, without prejudice to other outstanding payments, to demand immediate refund of outstanding advances. 4. If preparatory operations for construction or supply of goods or services require prior commitment of funds, advance payments may be made to the contractor to carry out these operations. The cause, the amount and the terms of payment of such advances shall be stated in the special conditions of contract for each individual contract. Final Page 34