; (2) in paragraph (6) by striking the period at the end and inserting ; and ; and (3) by adding at the end the following: (7) $842,076,502 for the period beginning on October 1, 2023, and ending on December 31, 2023. . (b) Obligation authority Subject to limitations specified in advance in appropriation Acts, sums made available pursuant to the amendment made by subsection (a) may be obligated at any time through September 30, 2024, and shall remain available until expended. (c) Program implementation For purposes of calculating funding apportionments and meeting other requirements under sections 47114, 47115, 47116, and 47117 of title 49, United States Code, for the period beginning on October 1, 2023, and ending on December 31, 2023, the Administrator of the Federal Aviation Administration shall— (1) first calculate such funding apportionments on an annualized basis as if the total amount available under section 48103 of such title for fiscal year 2024 was $3,350,000,000; and (2) then reduce by 75 percent— (A) all funding apportionment amounts calculated under paragraph (1); and (B) amounts made available pursuant to subsections (b) and (f)(2) of section 47117 of such title. (d) Extension of project grant authority Section 47104(c) of title 49, United States Code, is amended in the matter preceding paragraph (1) by striking September 30, 2023, and inserting December 31, 2023, . (e) Extension of special rule for apportionments Section 47114(c)(1)(J) of title 49, United States Code, is amended by striking 2023 to and inserting 2023, and for the period beginning on October 1, 2023, and ending on December 31, 2023, to . 2202. Extension of expiring authorities