(D) of section 215(i)(1) of the Social Security Act ( 42 U.S.C. 415(i)(1) ) (relating to cost-of-living increases in Social Security benefits) is amended to read as follows: (D) (i) the term CPI increase percentage , with respect to a base quarter or cost-of-living quarter in any calendar year, means the percentage (rounded to the nearest one-tenth of 1 percent) by which the Consumer Price Index for that quarter (as prepared by the Department of Labor) exceeds such index for the most recent prior calendar quarter which was a base quarter under subparagraph (A)(ii) or, if later, the most recent cost-of-living computation quarter under subparagraph (B), (ii) if the Consumer Price Index (as so prepared) does not include the national sales tax paid, then the term CPI increase percentage , with respect to a base quarter or cost-of-living quarter in any calendar year, means the percentage (rounded to the nearest one-tenth of 1 percent) by which the product of— (I) the Consumer Price Index for that quarter (as so prepared), and (II) the national sales tax factor, exceeds such index for the most recent prior calendar quarter which was a base quarter under subparagraph (A)(ii) or, if later, the most recent cost of living computation quarter under subparagraph (B), and (iii) the national sales tax factor is equal to 1 plus the quotient that is— (I) the sales tax rate imposed by section 101 of the Internal Revenue Code of 2017, divided by (II) the quantity that is 1 minus such sales tax rate. . IV Sunset of Sales Tax if Sixteenth Amendment not Repealed 401. Elimination of sales tax if Sixteenth Amendment not repealed If the Sixteenth Amendment to the Constitution of the United States is not repealed before the end of the 7-year period beginning on the date of the enactment of this Act, then all provisions of, and amendments made by, this Act shall not apply to any use or consumption in any year beginning after December 31 of the calendar year in which or with which such period ends, except that the Sales Tax Bureau of the