used in such section. (2) Small employer The term small employer means an eligible employer (as defined in section 408(p)(2)(C)(i)). (d) Denial of double benefit No deduction shall be allowable under this title for any contribution with respect to which a credit is allowed under this section. . (b) Credit To be part of general business credit Subsection (b) of section 38 is amended by striking plus at the end of paragraph (31), by striking the period at the end of paragraph (32) and inserting , plus , and by adding at the end the following new paragraph: (33) the safe harbor adoption credit determined under section 45T. . (c) Clerical amendment The table of sections for subpart D of part IV of subchapter A of chapter 1 is amended by adding after the item relating to section 45S the following new item: Sec. 45T. Credit for small employers with respect to modified safe harbor requirements for automatic contribution arrangements. . (d) Effective date The amendments made by this section shall apply to taxable years which include any portion of a plan year beginning after December 31, 2018. 104. Expansion of saver's credit (a) Expansion Paragraph (1) of section 25B(b) is amended by striking $32,500 both places it appears in subparagraphs (B) and (C) of paragraph (1) and inserting $40,000 . (b) Testing period Subparagraph (B) of section 25B(d)(2) is amended to read as follows: (B) Testing period For purposes of subparagraph (A), the testing period, with respect to a taxable year, is the period which includes— (i) such taxable year, and (ii) the 3 preceding taxable years. . (c) Treatment as refundable (1) Credit moved to subpart relating to refundable credits (A) In general The Internal Revenue Code of 1986 is amended— (i) by redesignating section 25B, as amended by this Act, as section 36C