; U.S. city average) as of September of the calendar year described in clause (i). (II) Rounding Any dollar amount determined under subclause (I) that is not a multiple of $100 shall be rounded to the next greatest multiple of $100. ; and (B) in paragraph (2), by adding at the end the following: (D) Adjustment for inflation (i) In general In the case of a calendar year described in subparagraph (A) that is after 2018, the dollar amount in such subparagraph shall be the dollar amount determined under this clause (or such subparagraph) for the previous year increased by the annual percentage increase (if any) in the consumer price index (all items; U.S. city average) as of September of the calendar year described in such subparagraph. (ii) Rounding Any dollar amount determined under clause (i) that is not a multiple of $100 shall be rounded to the next greatest multiple of $100. ; (2) by redesignating subsection (b) as subsection (c); (3) by inserting after subsection (a) the following: (b) Calculating income of household (1) Adjusted gross income For purposes of subsection (a)(1)(A), the adjusted gross income of a household for a taxable year is the sum of the adjusted gross incomes of the individuals who are members of the household at the end of the year. (2) Modified adjusted gross income For purposes of subsection (a)(1)(B), the modified adjusted gross income of a household for a taxable year is the sum of the modified adjusted gross incomes of the individuals who are members of the household at the end of the year. ; and (4) in subsection (c), as so redesignated by paragraph (2) of this subsection— (A) by striking , including and all that follows and inserting a period; (B) by striking The Secretary and inserting the following: (1) In general The Secretary