(a) “Contractor” as including “subcontractor.” Except where otherwise noted or where the term Government prime contractor is used, the term contractor as used in this part 4 shall be deemed to include a subcontractor. The term contractor as used in the contract clauses required by subpart A in any subcontract under a covered contract shall be deemed to refer to the subcontractor, or, if in a subcontract entered into by such a subcontractor, shall be deemed to refer to the lower level subcontractor. (See § 4.1a(f).)

(b) Liability of prime contractor. When a contractor undertakes a contract subject to the Act, the contractor agrees to assume the obligation that the Act's labor standards will be observed in furnishing the required services. This obligation may not be relieved by shifting all or part of the work to another, and the prime contractor is jointly and severally liable with any subcontractor for any underpayments on the part of a subcontractor which would constitute a violation of the prime contract. The prime contractor is required to include the prescribed contract clauses (§§ 4.6-4.7) and applicable wage determination in all subcontracts. The appropriate enforcement sanctions provided under the Act may be invoked against both the prime contractor and the subcontractor in the event of failure to comply with any of the Act's requirements where appropriate under the circumstances of the case.