23 C.F.R. § 140.807 – Reimbursable costs.

(a) Federal funds may be used to reimburse an SHA for the following types of project related audit costs:
1. (1) Salaries, wages, and related costs paid to public employees in accordance with subpart G of this part,
2. (2) Payments by the SHA to any Federal, State, or local public agency audit organization, and
3. (3) Payments by the SHA to licensed or certified public accounting firms.
(b) Audit costs incurred by an SHA shall be equitably distributed to all benefiting parties. The portion of these costs allocated to the Federal-Aid Highway Program which are not directly related to a specific project or projects shall be equitably distributed, as a minimum, to the major FHWA funding categories in that State.