Section 24(d) is amended by inserting after paragraph (3) the following new paragraph: (4) Adjustment for inflation (A) In general In the case of a taxable year beginning after 2018, the $1,400 amount in paragraph (1)(A)(i) shall be increased by an amount equal to— (i) such dollar amount, multiplied by (ii) the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which the taxable year begins, determined by substituting 2017 for 2016 in subparagraph (A)(ii) thereof. (B) Rounding If any increase under subparagraph (A) is not a multiple of $100, such increase shall be rounded to the next lowest multiple of $100. (C) Limitation The amount of any increase under subparagraph (A) (after the application of subparagraph (B)) shall not exceed $600. . (4) Conforming amendments (A) Section 24(e) is amended to read as follows: (e) Taxpayer identification requirement No credit shall be allowed under this section if the identifying number of the taxpayer was issued after the due date for filing the return of tax for the taxable year. . (B) Section 24 is amended by striking subsection (h). (c) Effective date The amendments made by this section shall apply to taxable years beginning after December 31, 2017. 123. Increased limitation for certain charitable contributions (a) In general Section 170(b)(1)(G) is amended to read as follows: (G) Cash contributions (i) In general Any contribution of cash to an organization described in subparagraph (A) shall be allowed to the extent that the aggregate of such contributions does not exceed 60 percent of the taxpayer’s contribution base for the taxable year, reduced by the aggregate amount of contributions allowable under subparagraph (A) for such taxpayer for such year. (ii) Carryover If the aggregate amount of contributions described in clause (i) exceeds the limitation of clause (i), such excess shall be treated (in a manner consistent with the rules of subsection (d)(1)) as a charitable contribution to which clause (i) applies in each of the 5