percentage with respect to any building to which amounts are allocated under clause (i) shall be determined under subsection (b)(2). (iv) Allocations treated as made first from additional allocation amount for purposes of determining carryover For purposes of determining the unused State housing credit ceiling under subparagraph (C) for any calendar year, any increase in the State housing credit ceiling under clause (i) shall be treated as an amount described in clause (ii) of such subparagraph. (v) Qualifying disaster area For purposes of this subparagraph, the term qualifying federally declared disaster area means— (I) each county which is determined to warrant individual or individual and public assistance from the Federal Government under a qualifying natural disaster declaration described in clause (vi)(I), and (II) each county not described in subclause (I) which is included in the geographical area covered by a qualifying natural disaster declaration described in subclause (II) or (III) of clause (vi). (vi) Qualifying natural disaster declaration For purposes of clause (v), the term qualifying natural disaster declaration means— (I) a federally declared disaster (as defined in section 165(i)(5)) occurring after December 31, 2011, and before January 1, 2023, or (II) a natural disaster declared by the Secretary of Agriculture. . (b) Eligibility for difficult development area For purposes of section 42 of the Internal Revenue Code of 1986, any area located in a disaster area (as defined in section 165(i)(5)(B) of the Internal Revenue Code of 1986) shall be designated a difficult development area for purposes of section 42(d)(5)(B)(iii) of such Code for any 24-month period following the date of a federally declared disaster, if the area qualifies to be such a difficult development area at any time within such 24-month period. (c) Effective date The amendment made by this section shall take effect on the date of the enactment of this Act. II Permanent disaster tax relief provisions 201. Exclusion for disaster