to years of participation Credit shall be determined under subsection (a) with respect to contributions made on behalf of an employee who is not a highly compensated employee only during the first 5 years such employee participates in the qualified automatic contribution arrangement. (c) Definitions (1) In general Any term used in this section which is also used in section 401(k)(14) shall have the same meaning as when 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 of the Internal Revenue Code of 1986, as amended by section 7, is further amended— (1) by striking plus at the end of paragraph (36), (2) by striking the period at the end of paragraph (37) and inserting , plus , and (3) by adding at the end the following new paragraph: (38) 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 of the Internal Revenue Code of 1986, as amended by section 7, is further 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 that include any portion of a plan year beginning after December 31, 2017. 10. Modification of regulations The Secretary of the Treasury shall promulgate regulations or other guidance that— (1) simplify and clarify the rules regarding the timing of participant notices required under section 401(k)(13)(E) of the Internal Revenue Code of 1986, with specific application to— (A) plans that allow employees to be eligible for participation