29 C.F.R. § 4.110
The Act covers service contracts of the Federal agencies described in §§ 4.107-4 .108. Except as otherwise specifically provided (see §§ 4.115 et seq.), all such contracts, the principal purpose of which is to furnish services in the United States through the use of service employees, are subject to its terms. This is true of contracts entered into by such agencies with States or their political subdivisions, as well as such contracts entered into with private employers. Contracts between a Federal or District of Columbia agency and another such agency are not within the purview of the Act; however, "subcontracts" awarded under "prime contracts" between the Small Business Administration and another Federal agency pursuant to various preferential set-aside programs, such as the 8(a) program, are covered by the Act. It makes no difference in the coverage of a contract whether the contract services are procured through negotiation or through advertising for bids. Also, the mere fact that an agreement is not reduced to writing does not mean that the contract is not within the coverage of the Act. The amount of the contract is not determinative of the Act's coverage, although the requirements are different for contracts in excess of $2,500 and for contracts of a lesser amount. The Act is applicable to the contract if the principal purpose of the contract is to furnish services, if such services are to be furnished in the United States, and if service employees will be used in providing such services. These elements of coverage will be discussed separately in the following sections.
29 C.F.R. §4.110