(D), applied— (I) by substituting unused qualified single-family housing carryover for unused housing credit carryover in clause (i) thereof, (II) without regard to clause (ii) thereof, (III) by substituting unused qualified single-family housing carryovers for unused housing credit carryovers in clause (iii) thereof, and (IV) by substituting an amount equal to its entire qualified single-family housing amount to projects described in paragraph (9) for entire State housing credit ceiling (determined without regard to amounts described in subparagraph (C)(v)) in clause (iv)(I) thereof. . (2) Conforming amendments (A) Section 42(h)(3)(C) of such Code is amended by inserting (other than amounts allocated from the qualified single-family housing amount) after the housing credit dollar amount previously allocated within the State . (B) Section 42(h)(3)(D) of such Code is amended by inserting (determined without regard to amounts described in subparagraph (C)(v)) after entire State housing credit ceiling . (c) Set aside of increased amounts Section 42(h) of the Internal Revenue Code of 1986 is amended by adding at the end the following new paragraph: (9) Set aside of qualified single-family housing amount The portion of the State housing credit ceiling which is equal to the qualified single-family housing amount for any calendar year shall be allocated to projects consisting of 1 to 4 dwelling units that are located in qualified census tracts (as defined in subsection (d)(5)(B)(i)). . (d) Effective date The amendments made by this section shall apply to allocations made for calendar years beginning after the date of the enactment of this Act.