as are necessary to carry out the purposes of this subparagraph, including for determining the area median purchase price with respect to different localities. (4) Inflation adjustment In the case of any taxable year beginning in a calendar year after 2024, each of the dollar amounts in paragraph (1) shall be increased by an amount equal to— (A) such dollar amount, multiplied by (B) the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which the taxable year begins, determined by substituting calendar year 2023 for calendar year 2016 in subparagraph (A)(ii) thereof. Any increase determined under the preceding sentence shall be rounded to the nearest multiple of $100. (5) Age limitation No credit shall be allowed under subsection (a) with respect to the purchase of any residence unless the taxpayer has attained age 18 as of the date of such purchase. In the case of any taxpayer who is married (within the meaning of section 7703), the taxpayer shall be treated as meeting the age requirement of the preceding sentence if the taxpayer or the taxpayer’s spouse meets such age requirement. (c) Definitions For purposes of this section— (1) First-time homebuyer The term first-time homebuyer means any individual if such individual (and if married, such individual’s spouse)— (A) has no present ownership interest in any residence during the 3-year period ending on the date of the purchase of the principal residence to which this section applies, and (B) has not taken the credit in any other taxable year. (2) Principal residence The term principal residence has the same meaning as when used in section 121. (3) Purchase (A) In general The term purchase means any acquisition, but only if— (i) the property is not acquired from a person related to the person acquiring such property (or, if married, such individual’s spouse), (ii) the acquisition is financed through a federally backed mortgage loan (as defined in section 4022 of the CARES Act), and (iii) the basis of the property in the hands of