for such taxable year, and (2) the amount determined under this subsection for the preceding taxable year, reduced by the sum of— (A) the distributions out of the accounts for the taxable year, and (B) the excess (if any) of— (i) the maximum amount allowable as a contribution under section 408B(c)(2)(A) for such taxable year, over (ii) the amount contributed to such accounts for such taxable year, and (3) the excess (if any) of— (A) the excess (if any) of— (i) the aggregate amounts contributed to such accounts for all taxable years, over (ii) the aggregate amount allowable as contributions under section 408B(c)(2)(B) for all taxable years, over (B) the amount determined under this paragraph for all preceding taxable years. . (c) Conforming amendment The table of sections for subpart A of part I of subchapter D of chapter 1 of such Code is amended by inserting after the item relating to section 408A the following new item: Sec. 408B. Small Business Start-up Savings Accounts. . (d) Effective date The amendments made by this section shall apply to taxable years beginning after December 31, 2017.