the percentage (if any) by which— (A) the CPI for the preceding calendar year, exceeds (B) the CPI for the calendar year 2017. (3) CPI for any calendar year For purposes of paragraph (2), the CPI for any calendar year is the average of the Consumer Price Index as of the close of the 12-month period ending on August 31 of such calendar year. (4) Consumer Price Index For purposes of paragraph (3), the term Consumer Price Index means the last Consumer Price Index for all urban consumers published by the Department of Labor. For purposes of the preceding sentence, the revision of the Consumer Price Index which is most consistent with the Consumer Price Index for calendar year 1986 shall be used. (5) Rounding If any increase determined under paragraph (1) is not a multiple of $10, such increase shall be rounded to the next highest multiple of $10. (g) Marital status For purposes of this section, marital status shall be determined under section 7703. 60B. Tax imposed on business activities (a) Tax imposed There is hereby imposed on every person engaged in a business activity who makes an election to be taxed under this part a tax equal to— (1) 19 percent of the business taxable income of such person for such taxable year in the case of the first 2 taxable years of the person beginning with the taxable year for which the election is made, and (2) 17 percent of the business taxable income of such person for such taxable year in the case of all taxable years subsequent to the taxable years described in paragraph (1). (b) Liability for tax The tax imposed by this section shall be paid by the person engaged in the business activity, whether such person is an individual, partnership, corporation, or otherwise. (c) Business taxable income For purposes of this section— (1) In general The term business taxable income means gross active income reduced by the deductions specified in subsection (d). (2) Gross active income (A) In general For purposes of paragraph (1), the term gross active income means gross receipts from— (i)