(A) Monthly specified child allowance In the case of any month beginning after December 31, 2023, each dollar amount in paragraph (1) shall be increased by an amount equal to— (i) such dollar amount, multiplied by— (ii) the percentage (if any) by which— (I) the CPI (as defined in section 1(f)(4)) for the calendar year preceding the calendar year in which such month begins, exceeds (II) the CPI (as so defined) for calendar year 2020. (B) Initial threshold amount In the case of any taxable year beginning after December 31, 2023, the dollar amounts in subclauses (I) and (III) of paragraph (2)(D)(i) shall each be increased by an amount equal to— (i) such dollar amount, multiplied by (ii) the percentage (if any) which would be determined under subparagraph (A)(ii) if subclause (II) thereof were applied by substituting 2022 for 2020 . (C) Rounding (i) Monthly specified child allowance Any increase under subparagraph (A) which is not a multiple of $10 shall be rounded to the nearest multiple of $10. (ii) Initial threshold amount Any increase under subparagraph (B) which is not a multiple of $5,000 shall be rounded to the nearest multiple of $5,000. (c) Specified child For purposes of this section— (1) In general The term specified child means, with respect to any taxpayer for any calendar month, an individual— (A) who has the same principal place of abode as the taxpayer for more than one-half of such month, (B) who is younger than the taxpayer and will not, as of the close of such month, have attained age 18, (C) who receives care from the taxpayer during such month that is not compensated, (D) who is not the spouse of the taxpayer at any time during such month, and (E) who either— (i) is a citizen, national, or resident of the United States, or (ii) if the taxpayer is a citizen or national of the United States, such individual is described in section 152(f)(1)(B) with respect to such taxpayer. (2) Certain individuals ineligible In the case of an individual who is a specified child with respect to another taxpayer for