made to the custodial account (without the establishment or maintenance of another plan under this subsection), or before the employee dies . (d) Effective date The guidance issued under subsections (a) and (b), and the amendments made by subsection (c), shall apply to taxable years beginning after December 31, 2008. 309. Permit plans to use base pay or rate of pay calculation (a) In general Not later than December 31, 2019, the Secretary of the Treasury shall modify Treasury Regulation section 1.414(s)–1(d)(3) to facilitate the use of the safe harbors in sections 401(k)(12), 401(k)(13), 401(k)(15), 401(m)(11), 401(m)(12), and 401(m)(13) of the Internal Revenue Code of 1986, and in Treasury Regulation section 1.401(a)(4)–3(b), by plans which use base pay or rate of pay in determining contributions or benefits. Such facilitation shall include increased flexibility in meeting the definition in section 414(s) of such Code in situations where the amount of overtime compensation payable in a year can vary significantly. (b) Exception The Secretary of the Treasury may make any modification under subsection (a) inapplicable to plans with respect to which, on a consistent basis, overtime is a major component of a substantial portion of the employees eligible to participate in the plan who are not highly compensated employees (as defined in section 414(q) of the Internal Revenue Code of 1986). 310. Roth SIMPLE IRAs (a) In general Section 408A(f) is amended— (1) by striking or a simple retirement account in paragraph (1)