an amount equal to the advance refund amount for such taxable year. (2) Advance refund amount For purposes of paragraph (1), the advance refund amount is the amount that would have been allowed as a credit under this section for such first taxable year if this section (other than subsection (f) and this subsection) had applied to such taxable year. (3) Timing of payments The Secretary shall, subject to the provisions of this title, refund or credit any overpayment attributable to this section as rapidly as possible. No refund or credit shall be made or allowed under this subsection after December 31, 2020. (4) No interest No interest shall be allowed on any overpayment attributable to this section. (5) Alternate taxable year In the case of an individual who, at the time of any determination made pursuant to paragraph (3), has not filed a tax return for the year described in paragraph (1), the Secretary may apply such paragraph by substituting 2019 for 2018 . (h) Identification number requirement (1) In general No credit shall be allowed under subsection (a) to an eligible individual who does not include on the return of tax for the taxable year— (A) such individual’s valid identification number, (B) in the case of a joint return, the valid identification number of such individual’s spouse, and (C) in the case of any qualifying child taken into account under subsection (b)(1)(B), the valid identification number of such qualifying child. (2) Valid identification number (A) In general For purposes of paragraph (1), the term valid identification number means a social security number (as such term is defined in section 24(h)(7)). (B) Adoption taxpayer identification number For purposes of paragraph (1)(C), in the case of a qualifying child who is adopted, the term valid identification number shall include the adoption taxpayer identification number of such child. (i) Regulations The Secretary shall prescribe such regulations or other guidance as may be necessary to carry out the purposes of this section. . (b)