25 C.F.R. § 162.017 : Indians — BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR — LAND AND WATER — LEASES AND PERMITS — GENERAL PROVISIONS —LEASE ADMINISTRATION — What taxes apply to leases approved under this part?

(a) Subject only to applicable Federal law, permanent improvements on the leased land, without regard to ownership of those improvements, are not subject to any fee, tax, assessment, levy, or other charge imposed by any State or political subdivision of a State. Improvements may be subject to taxation by the Indian tribe with jurisdiction.
(b) Subject only to applicable Federal law, activities under a lease conducted on the leased premises are not subject to any fee, tax, assessment, levy, or other charge (e.g., business use, privilege, public utility, excise, gross revenue taxes) imposed by any State or political subdivision of a State. Activities may be subject to taxation by the Indian tribe with jurisdiction.
(c) Subject only to applicable Federal law, the leasehold or possessory interest is not subject to any fee, tax, assessment, levy, or other charge imposed by any State or political subdivision of a State. Leasehold or possessory interests may be subject to taxation by the Indian tribe with jurisdiction.

25 C.F.R. § 162.017