a calendar year if— (I) the aggregate value of a designated beneficiary’s entire interest acquired by such beneficiary during the calendar year under all such plans of the employer by reason of the death of the employee does not exceed the dollar amount in effect for such year under clause (i), and (II) the designated beneficiary certifies, within 1 year after the death of the employee from whom the beneficiary acquired the interest, that the aggregate value of the designated beneficiary’s entire interest acquired by such beneficiary during the calendar year under all defined contribution plans by reason of the death of another individual does not exceed the dollar amount in effect for such year under clause (i). For purposes of this clause, the value of any interest shall be determined as of the date of the death of the individual from whom the beneficiary acquired such interest, and all employers treated as a single employer under subsection (b), (c), (m), or (o) of section 414 shall be treated as a single employer. (viii) Application to eligible retirement plans For purposes of applying the provisions of this subparagraph and subsections (a)(6) and (b)(3) of section 408, all eligible retirement plans (as defined in section 402(c)(8)(B)) other than defined benefit plans shall be treated as defined contribution plans in determining the aggregate account balances to the credit of the designated beneficiary under all defined contribution plans and the amount required to be distributed to each beneficiary under such provisions. (ix) Adjustment for inflation In the case of any taxable year beginning after 2020, the $400,000 amount in clause (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 calendar year 2019 for calendar year 2016 in subparagraph (A)(ii) thereof. If any amount as adjusted under the preceding sentence is not a