49 U.S.C. § 47109 — United States Government’s share of project costs

(a) General — Except where this section says otherwise, the government's normal share of an airport project's allowable costs is: 75 percent at a medium or large hub airport; up to 90 percent for a project funded through a State's block grant under section 47128; 90 percent at any other airport; 70 percent for a project the Administrator funds from the discretionary fund under section 47115 at an airport with an exemption under section 47134; and 95 percent for a project that (A) the Administrator decides is a later phase of a multi-phase construction project that got a grant in fiscal year 2011, and (B) would otherwise be capped at 90 percent under paragraph (2) or (3). (b) Increased Government Share — Some states have more than 5 percent of their land as unclaimed public land or non-taxable Indian land. If a project's normal share under (a) would be lower than the share that state got on June 30, 1975, under the old law, the government's share goes up — but only by the smallest of three numbers: 25 percentage points; half the percentage of the state's land that is that kind of public or Indian land; or whatever amount restores the 1975 share exactly. (c) Grandfather Rule — (1) For a small-hub or nonhub airport project approved after September 30, 2003, in one of those public-land states, the government's share rises using a fixed ratio the FAA published on August 3, 1979, comparing the normal 80 percent share to the higher "public lands state" share that applied that day. This only applies if the state had that same land makeup back on August 3, 1979, and if the increase under (b) does not already apply. (2) Even with this boost, the government's share can never exceed the lesser of 93.75 percent or the highest share any project gets under (b) — except that a small non-primary airport within 15 miles of another qualifying state gets the average of both states' shares. (d) Privately Owned Reliever Airports — If a privately owned reliever airport donates land, easements, or rights-of-way for a project, the current fair market value of what it gave counts toward the airport's own, non-federal, share of the costs. (e) Small Hub to Medium Hub Transition — If a small hub airport becomes a medium hub airport, its government cost-share cannot go above 90 percent for the first two fiscal years after the change. (f) Economically Distressed Communities — The government's share is 95 percent for a project at an airport that (1) gets subsidized essential air service and (2) sits in an area that meets the Commerce Department's economic-distress criteria under the Public Works and Economic Development Act. (g) Covered Equipment — (1) The government's share for "covered equipment" and its installation is 100 percent. (2) "Covered equipment" means input-based aqueous film forming foam testing equipment eligible for Airport Improvement Program funding under a specific 2021 FAA guidance letter, PGL 21-01, or any later version of it. (3) This 100 percent rate ends on whichever comes first: 180 days after that equipment stops being eligible for Airport Improvement Program funding, or 5 years after this rule was enacted. (h) Special Rule for Fiscal Years 2025 and 2026 — Regardless of the normal shares in (a), a grant to a nonhub or nonprimary airport gets a 95 percent government share in each of fiscal years 2025 and 2026. (i) Sound Insulation Repair and Replacement — For a sound-insulation project that got a waiver under section 47110(j), the allowable project cost is figured without counting any costs the government already paid for earlier.