; and (iv) the term excess self-employment income means that portion of the self-employment income of an individual credited to a year after 2017 in excess of the higher of $300,000 or such contribution and benefit base. . (c) Conforming amendment Section 215(e)(1) of the Social Security Act ( 42 U.S.C. 415(e)(1) ) is amended by inserting and before 2018 after 1974 . (d) Effective date The amendments made by this section shall apply with respect to individuals who initially become eligible (within the meaning of section 215(a)(3)(B) of the Social Security Act) for old-age or disability insurance benefits under title II of the Social Security Act, or who die (before becoming eligible for such benefits), in any calendar year after 2017. 4. Modification of amount of social security benefits included in gross income (a) In general Section 86 of the Internal Revenue Code of 1986 is amended by striking subsections (a), (b), and (c) and inserting the following: (a) In general Gross income for the taxable year of any taxpayer described in subsection (b) (notwithstanding section 207 of the Social Security Act) includes social security benefits in an amount equal to the lesser of— (1) 85 percent of the social security benefits received during the taxable year, or (2) 85 percent of the excess described in subsection (b). (b) Taxpayers to whom subsection (a) applies A taxpayer is described in this subsection if— (1) the sum of— (A) the modified adjusted gross income of the taxpayer for the taxable year, plus (B) 85 percent of the social security benefits received during the taxable year, exceeds (2) $100,000. (c) Modified adjusted gross income For purposes of this section, the term modified adjusted gross income means adjusted gross income— (1) determined without regard to this section and sections 135, 137, 199, 221, 222, 911, 931, and 933, and (2) increased by the amount of interest received or accrued by the taxpayer during the taxable year which is exempt from tax. . (b) Social security trust funds held harmless There