; (2) $2,000,000 shall be for the cost of guaranteed notes and other obligations, as authorized by title VI of NAHASDA: Provided, That such costs, including the costs of modifying such notes and other obligations, shall be as defined in section 502 of the Congressional Budget Act of 1974 ( 2 U.S.C. 661a ): Provided further, That for fiscal year 2021, the Secretary may subsidize the total principal amount of any notes and other obligations, any part of which is to be guaranteed, not to exceed $61,298,904: Provided further, That any unobligated balances, including recaptures and carryover, remaining from amounts appropriated for this purpose under this heading or under the heading Native American Housing Block Grants in prior Acts may be used for costs of such guaranteed notes and other obligations, subject to the limitation under the preceding proviso on the total principal amount of such notes and obligations that may be guaranteed