of the Internal Revenue Code of 1986 is amended by inserting after such calendar year. the following: The preceding sentence shall apply only to calendar years for which the contribution and benefit base (as so determined) is less than $400,000, and, for such calendar years, only to the extent remuneration paid to such employee by such employer with respect to employment does not exceed $400,000. . (B) Conforming amendment Paragraph (1) of section 3121(a) of the Internal Revenue Code of 1986 is amended by striking Act) to and inserting Act), or in excess of $400,000, to . (2) Amendment to the Social Security Act Section 209(a)(1)(I) of the Social Security Act ( 42 U.S.C. 409(a)(1)(I) ) is amended by inserting before the semicolon at the end the following: except that this subparagraph shall apply only to calendar years for which the contribution and benefit base (as so determined) is less than $400,000, and, for such calendar years, only to the extent remuneration paid to such employee by such employer with respect to employment does not exceed $400,000 . (3) Effective date The amendments made by this subsection shall apply with respect to remuneration paid in calendar years after 2018. (b) Determination of self-Employment income above contribution and benefit base after 2018 (1) Amendments to the Internal Revenue Code (A) In general Paragraph (1) of section 1402(b) of the Internal Revenue Code of 1986 is amended to read as follows: (1) in the case of the tax imposed by section 1401(a), an amount equal to— (A) $400,000, reduced (but not below zero) by (B) the sum of— (i) the part of the net earnings from self-employment (if any) which is not in excess of— (I) the amount equal to the contribution and benefit base (as determined under section 230 of the Social Security Act) which is effective for the calendar year in which such taxable year begins, minus (II) the amount of the wages paid to such individual during such taxable year, plus (ii) the amount of the wages paid to such individual during such taxable year