the case of any taxable year beginning after December 31, 2019, the product of— (i) $400,000, and (ii) the quotient obtained by dividing— (I) the national average wage index (as defined in section 209(k)(1)) for the calendar year which is 2 years before the calendar year in which the taxable year begins, by (II) the national average wage index for calendar year 2017. . 5. Inclusion of surplus earnings in social security benefit formula (a) Inclusion of surplus average indexed monthly earnings in determination of primary insurance amounts Section 215(a)(1)(A) of the Social Security Act ( 42 U.S.C. 415(a)(1)(A) ) is amended— (1) in clauses (i), (ii), and (iii), by inserting basic before average indexed monthly earnings each place it appears