29 CFR 10.21: Contract clause.

(a) Contract clause. The contractor, as a condition of payment, shall abide by the terms of the applicable Executive Order minimum wage contract clause referred to in § 10.11(a).

(b) The contractor and any subcontractors shall include in any covered subcontracts the Executive Order minimum wage contract clause referred to in § 10.11(a) and shall require, as a condition of payment, that the subcontractor include the minimum wage contract clause in any lower-tier subcontracts. The prime contractor and any upper-tier contractor shall be responsible for the compliance by any subcontractor or lower-tier subcontractor with the Executive Order minimum wage requirements, whether or not the contract clause was included in the subcontract.