29 CFR §4.140

As set forth in § 4.104 and in the requirements of §§ 4.6-4.7, the obligations of a contractor with respect to labor standards differ in the case of a covered and nonexempt contract, depending on whether the contract is or is not in excess of $2,500. Rules for resolving questions that may arise as to whether a contract is or is not in excess of this figure are set forth in the following sections.