new subparagraph: (I) Protected participants (i) In general A plan shall be deemed to satisfy the requirements of subparagraph (A) if— (I) the plan is amended— (aa) to cease all benefit accruals, or (bb) to provide future benefit accruals only to a closed class of participants, (II) the plan satisfies subparagraph (A) (without regard to this subparagraph) as of the effective date of the amendment, and (III) the amendment was adopted before September 21, 2016, or the plan is described in clause (ii). (ii) Plans described A plan is described in this clause if the plan would be described in subsection (o)(1)(C), as applied for purposes of subsection (o)(1)(B)(iii)(IV) and by treating the effective date of the amendment as the date the class was closed for purposes of subsection (o)(1)(C). (iii) Special rules For purposes of clause (i)(II), in applying section 410(b)(6)(C), the amendments described in clause (i) shall not be treated as a significant change in coverage under section 410(b)(6)(C)(i)(II). (iv) Spun-off plans For purposes of this subparagraph, if a portion of a plan described in clause (i) is spun off to another employer, the treatment under clause (i) of the spun-off plan shall continue with respect to the other employer. . (c) Effective 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 September 21, 2016, if the