taxable year, and (ii) the Secretary determines that there was reasonable cause for the failure to timely make such revocation, the Secretary may treat such a revocation as timely made for such taxable year. . (d) Effective date (1) In general Except as otherwise provided in this subsection, the amendments made by this section shall apply to elections for taxable years beginning after December 31, 2017. (2) Revocations The amendments made by subsection (c) shall apply to revocations after December 31, 2017.