29 C.F.R. § 5.23
Pursuant to the Davis-Bacon Act, as amended and codified at 40 U.S.C. 3141(2) , the term "prevailing wages" and similar terms include the basic hourly rate of pay and, for the listed fringe benefits and other bona fide fringe benefits not required by other law, the contributions irrevocably made by a contractor or subcontractor to a trustee or third party pursuant to a bona fide fringe benefit fund, plan, or program, and the costs to the contractor or subcontractor that may be reasonably anticipated in providing bona fide fringe benefits pursuant to an enforceable commitment to carry out a financially responsible plan or program, which was communicated in writing to the affected laborers and mechanics. Section 5.29 discusses specific fringe benefits that may be considered to be bona fide.
29 C.F.R. §5.23