. (c) Automatic contribution arrangements Section 401(k)(13) of the Internal Revenue Code of 1986 is amended by adding at the end the following: (F) Timing of plan amendment for employer making nonelective contributions (i) In general Except as provided in clause (ii), a plan may be amended after the beginning of a plan year to provide that the requirements of subparagraph (D)(i)(II) shall apply to the arrangement for the plan year, but only if the amendment is adopted— (I) at any time before the 30th day before the close of the plan year, or (II) at any time before the last day under paragraph (8)(A) for distributing excess contributions for the plan year. (ii) Exception where plan provided for matching contributions Clause (i) shall not apply to any plan year if the plan provided at any time during the plan year that the requirements of subparagraph (D)(i)(I) or paragraph (12)(B) applied to the plan year. (iii) 4-percent contribution requirement Clause (i)(II) shall not apply to an arrangement unless the amount of the contributions described in subparagraph (D)(i)(II) which the employer is required to make under the arrangement for the plan year with respect to any employee is an amount equal to at least 4 percent of the employee's compensation. . (d) Effective date The amendments made by this section shall apply to plan years beginning after December 31, 2017. 6. Increase in credit limitation for small employer pension plan startup costs (a) In general Paragraph (1) of section 45E(b) of the Internal Revenue Code of 1986 is amended to read as follows: (1) for the first credit year and each of the 2 taxable years immediately following the first credit year, the greater of— (A) $500, or (B) the lesser of— (i) $250 for each employee of the eligible employer who is not a highly compensated employee (as defined in section 414(q)) and who is eligible to participate in the eligible employer plan maintained by the eligible employer, or (ii) $5,000, and . (b) Effective date The amendment made by this section shall