; (2) by striking the period at the end of paragraph (36) and inserting , plus ; and (3) by adding at the end the following new paragraph: (37) the safe harbor adoption credit determined under section 45S. . (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 is amended by adding after the item relating to section 45R the following new item: Sec. 45S. 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. 11. 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 immediately upon beginning employment; and (B) employers with multiple payroll and administrative systems