date (1) In general Except as provided in paragraph (2), the amendments made by this section shall take effect on the date of the enactment of this Act, without regard to whether any plan modifications referred to in such amendments are adopted or effective before, on, or after such date of enactment. (2) Special rules (A) Election of earlier application At the election of the plan sponsor, the amendments made by this section shall apply to plan years beginning after December 31, 2013. (B) Closed classes of participants For purposes of paragraphs (1)(A)(iii), (1)(B)(iii)(IV), and (2)(A)(iv) of section 401(o) of the Internal Revenue Code of 1986 (as added by this section), a closed class of participants shall be treated as being closed before April 5, 2017, if the plan sponsor’s intention to create such closed class is reflected in formal written documents and communicated to participants before such date. (C) Certain post-enactment plan amendments A plan shall not be treated as failing to be eligible for the application of section 401(o)(1)(A), 401(o)(1)(B)(iii), or 401(a)(26) of such Code (as added by this section) to such plan solely because in the case of— (i) such section 401(o)(1)(A), the plan was amended before the date of the enactment of this Act to eliminate 1 or more benefits, rights, or features, and is further amended after such date of enactment to provide such previously eliminated benefits, rights, or features to a closed class of participants, or (ii) such section 401(o)(1)(B)(iii) or section 401(a)(26), the plan was amended before the date of the enactment of this Act to cease all benefit accruals, and is further amended after such date of enactment to provide benefit accruals to a closed class of participants. Any such section shall only apply if the plan otherwise meets the requirements of such section and in applying such section, the date the class of participants is closed shall be the effective date of the later amendment. G Estate, gift, and generation-skipping transfer taxes 1601.