means— (A) the taxpayer’s first taxable year beginning in 2019, or (B) if information regarding such taxable year is not available to the Secretary (determined without regard to subsection (h)(1)), the taxpayer’s first taxable year beginning in 2018. (3) Timing of payments (A) In general The Secretary shall, subject to the provisions of this title, refund or credit any overpayment attributable to paragraph (1) as rapidly as possible. (B) Termination of payment authority No refund or credit shall be made or allowed under this subsection after December 31, 2020. (4) Coordination with payments to social security administration recipients This subsection shall not apply with respect to any taxpayer entitled to a payment under section 202 of the COVID-19 Tax Relief Act of 2020 . (5) No interest No interest shall be allowed on any overpayment attributable to this section. (6) Information provided to taxpayers As soon as practicable, the Secretary shall— (A) make best efforts to inform every taxpayer that amounts received pursuant to this subsection may be subject to recapture under subsection (f)(2), and (B) develop an Internet tool allowing taxpayers to determine the amount of such recapture using input from the taxpayer. (h) Regulations The Secretary shall prescribe such regulations or other guidance as may be necessary or appropriate to carry out the purposes of this section, including— (1) regulations or other guidance providing taxpayers with respect to whom information for neither taxable year described in subsection (g)(2) is available to the Secretary the opportunity to provide the Secretary information sufficient to allow the Secretary to determine the amount of the credit or refund for such taxpayer under subsection (g), and (2) regulations or other guidance providing for the proper treatment of joint returns and taxpayers with qualifying children if any individual taken into account under this section with respect to such joint return or by such taxpayer is an eligible individual (as defined in section