48 C.F.R. § 31.107
(a) Subpart 31.6 provides principles and standards for determining costs applicable to contracts with State, local, and federally recognized Indian tribal governments. They provide the basis for a uniform approach to the problem of determining costs and to promote efficiency and better relationships between State, local, and federally recognized Indian tribal governments, and Federal Government entities. They apply to all programs that involve contracts with State, local, and federally recognized Indian tribal governments, except contracts with—
[48 FR 42301, Sept. 19, 1983, as amended at 52 FR 30076, Aug. 12, 1987]