; or ; and (B) by adding at the end the following: (l) For purposes of subsection (b)(2), the applicable percentage for a taxable year beginning in any calendar year referred to in such paragraph shall be determined in accordance with the following table: The applicable In the case of: percentage is: Calendar year 2019 90 percent Calendar year 2020 80 percent Calendar year 2021 70 percent Calendar year 2022 60 percent Calendar year 2023 50 percent Calendar year 2024 40 percent Calendar year 2025 30 percent Calendar year 2026 20 percent Calendar year 2027 10 percent Calendar years after 2028 0 percent. . (3) Effective date The amendments made by this subsection shall apply with respect to taxable years beginning in calendar years after 2018. (c) Computing average indexed monthly earnings Section 215(e) of the Social Security Act ( 42 U.S.C. 415(e) ) is amended— (1) in paragraph (1)— (A) by striking and after before 1975, ; (B) by inserting and before 2019 after after 1974 ; and (C) by inserting , and the applicable percentage of the excess over an amount equal to the contribution and benefit base (as determined under section 230) in the case of any calendar year after 2016 with respect to which such contribution and benefit base is effective, after benefit base is effective,