40 CFR 35.575: Maximum federal share.

(a) For Tribes and Intertribal Consortia eligible under § 35.573(a), the Regional Administrator may provide financial assistance in an amount up to 95 percent of the approved costs of planning, developing, establishing, or improving an air pollution control program, and up to 95 percent of the approved costs of maintaining that program. After two years from the date of each Tribe's or Intertribal Consortium's initial grant award, the Regional Administrator will reduce the maximum federal share to 90 percent if the Regional Administrator determines that the Tribe or each member of the Intertribal Consortium meets certain economic indicators that would provide an objective assessment of the Tribe's or each of the Intertribal Consortiums member's ability to increase its share. For a Tribe or Intertribal Consortium eligible under § 35.573(a), the Regional Administrator may increase the maximum federal share if the Tribe or Intertribal Consortium can demonstrate in writing to the satisfaction of the Regional Administrator that fiscal circumstances within the Tribe or within the member Tribes of the Intertribal Consortium are constrained to such an extent that fulfilling the match requirement would impose undue hardship.

(b) For Tribes and Intertribal Consortia eligible under § 35.573(b), the Regional Administrator may provide financial assistance in an amount up to 60 percent of the approved costs of planning, developing, establishing, or improving an air pollution control program, and up to 60 percent of the approved costs of maintaining that program.

(c) Revenue collected under a Tribal Title V operating permit program may not be used to meet the cost share requirements of this section.