in subparagraph (A)(ii) (or, if earlier, the date the plan or contract amendment is adopted), the plan or contract is operated as if such plan or contract amendment were in effect, and (ii) such plan or contract amendment applies retroactively for such period. 402. Single-employer plan funding rules (a) Delay in payment of minimum required contributions In the case of any minimum required contribution (as determined under section 430(a) of the Internal Revenue Code of 1986 and section 303(a) of the Employee Retirement Income Security Act of 1974 ( 29 U.S.C. 1083(a) )) which (but for this section) would otherwise be due under section 430(j) of such Code (including quarterly contributions under paragraph (3) thereof) and section 303(j) of such Act ( 29 U.S.C. 1083(j) ) (including quarterly contributions under paragraph (3) thereof) during calendar year 2020— (1) such contributions shall not be required to be made until January 1, 2021, and (2) the amount of each such minimum required contribution shall be increased by interest accruing for the period between the original due date (without regard to this section) for the contribution and the payment date, at the effective rate of interest for the plan for the plan year which includes such payment date. (b) Benefit restriction status For purposes of section 436 of the Internal Revenue Code of 1986 and section 206(g) of the Employee Retirement Income Security Act of 1974 ( 29 U.S.C. 1056(g) ), a plan sponsor may elect to treat the plan's adjusted funding target attainment percentage for the last plan year ending before January 1, 2020, as the adjusted funding target attainment percentage for plan years which include calendar year 2020. 403. Temporary waiver of required minimum distribution rules for certain retirement plans and accounts (a) In general Section 401(a)(9) of the Internal Revenue Code of 1986 is amended by adding at the end the following new subparagraph: (I) Temporary waiver of minimum required distribution (i) In general The requirements of this