has the meaning given such term by section 3306(b) (determined without regard to any dollar limitation contained in such section). Such term shall not include any amount taken into account in determining any other credit allowed under this subpart. (2) Predecessor and successor Any reference in this paragraph to an employer shall include a reference to any predecessor of, or successor to, such employer. (3) Aggregation rule All persons treated as a single employer under subsection (b), (c), (m), or (o) of section 414 shall be treated as one employer. (4) Inflation adjustment (A) In general In the case of a taxable year beginning after 2018, the $500,000 and $75,000 amounts in subsections (b) and (c) shall each be increased by an amount equal— (i) such dollar amount, multiplied by (ii) the cost-of-living adjustment determined under subparagraph (B) for the calendar year in which the taxable year begins. (B) Cost-of-living adjustment For purposes of this paragraph, the cost-of-living adjustment for any calendar year is the percentage (if any) by which— (i) the CPI for the preceding calendar year, exceeds (ii) the CPI for calendar year 2017. (C) CPI for any calendar year For purposes of this paragraph, the CPI for any calendar year shall be determined as provided in section 1(f)(4). (D) Rounding If any amount as adjusted under subparagraph (A) is not a multiple of $1,000, such amount shall be rounded to the next lowest multiple of $1,000. (5) Election to have credit not apply A taxpayer may elect to have this section not apply for any taxable year. Rules similar to the rules of paragraphs (2) and (3) of section 51(j) shall apply for purposes of this paragraph. . (b) Credit To be part of general business credit Section 38(b) of such Code is amended by striking plus at the end of paragraph (36), by striking the period at the end of paragraph (37) and inserting , plus , and by inserting after paragraph (37) the following new paragraph: (38) the employer wage credit determined under section 45T. . (c) Denial of double