plans, etc A plan or arrangement to which a contribution is made under this section shall not be treated as violating any requirement under section 401, 403, 408, or 457 solely by reason of accepting such contribution. (4) Erroneous credits If any contribution is erroneously paid under subsection (a)(2), the amount of such erroneous payment shall be treated as an underpayment of tax. (g) Inflation adjustments (1) In general In the case of any taxable year beginning in a calendar year after 2018, each of the dollar amounts in subsections (a)(2) and (b)(3)(A)(i) shall be increased by an amount equal to— (A) such dollar amount, multiplied by (B) the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which the taxable year begins, determined by substituting calendar year 2017 for calendar year 1992 in subparagraph (B) thereof. (2) Rounding Any increase determined under paragraph (1) shall be rounded to the nearest multiple of— (A) $100 in the case of an adjustment of the amount in subsection (a)(2), and (B) $1,000 in the case of an adjustment of the amount in subsection (b)(3)(A)(i). . (b) Promotion and guidance (1) Promotion The Secretary of the Treasury (or the Secretary’s delegate) shall educate taxpayers on the benefits provided under section 6433 of the Internal Revenue Code of 1986. (2) Guidance Not later than December 31, 2017, the Secretary of the Treasury (or the Secretary’s delegate) shall issue guidance on the implementation and administration of the amendments made by this section. (c) Payment authority Section 1324(b)(2) of title 31, United States Code, is amended by striking or 6431 and inserting 6431, or 6433 . (d) Deficiencies Section 6211(b)(4) is amended by striking and 6431 and inserting 6431, and 6433 . (e) Conforming amendments (1) Section 25B of the Internal Revenue Code of 1986 is amended by striking subsections (a) through (f) and inserting the following: For payment of credit related to qualified retirement savings contributions, see section 6433. . (2) The