24 CFR § 1000.326 - What if a formula area is served by more than one Indian tribe?
(a) If an Indian tribe's formula area overlaps with the formula area of one or more other Indian tribes, the funds allocated to that Indian tribe for the geographic area in which the formula areas overlap will be divided based on:
(1) The Indian tribe's proportional share of the population in the overlapping geographic area; and
(2) The Indian tribe's commitment to serve that proportional share of the population in such geographic area.
(3) In cases where a State recognized tribe's formula area overlaps with the formula area of a Federally recognized Indian tribe, the Federally recognized Indian tribe receives the allocation for the formula area up to its population cap, and the State recognized tribe receives the balance of the overlapping area (if any) up to its population cap.
(b) Tribal membership in the geographic area (not to include dually enrolled tribal members) will be based on data that all Indian tribes involved agree to use. Suggested data sources include tribal enrollment lists, the U.S. Census, Indian Health Service User Data, and Bureau of Indian Affairs data.
(c) Upon receiving a request for expansion or redefinition of a tribe's formula area, if approving the request would create an overlap, HUD shall follow the notice and comment procedures set forth in paragraph (2)(ii) of the definition of “Formula area” in § 1000.302.
(d) If the Indian tribes involved cannot agree on what data source to use, HUD will make the decision on what data will be used to divide the funds between the Indian tribes by August 1.