The Fair Labor Standards Act (FLSA) does not require payment for time not worked, such as vacations or holidays (federal or otherwise). These benefits are generally a matter of agreement between an employer and an employee (or the employee's representative).
On a government contract to which the labor standards of the McNamara O'Hara Service Contract Act (SCA) apply, holiday and/or vacation fringe benefit requirements are stated in the SCA wage determinations in contracts that exceed $2,500.
On a government contract to which the labor standards of the Davis-Bacon and Related Acts apply, holiday pay and/or vacation pay is required for specific classifications of workers only if the Davis-Bacon wage determination in the covered contract specifies such requirements for workers employed in those classifications.
Regulations on this Topic
29 CFR Part 4.174 – Regulations on Meeting Requirements for Holiday Fringe Benefits for Federal Contracts Covered by the Service Contract Act