Effective dates

In the case of a plan maintained on January 1, 1974, pursuant to one or more agreements which the Secretary finds to be collective bargaining agreements between employee organizations and one or more employers, no plan shall be treated as not meeting the requirements of sections 1054 and 1055 of this title by reason of a supplementary or special plan provision (within the meaning of paragraph (2)) for any plan year before the year which begins after the earlier of— For purposes of paragraph (1), the term “supplementary or special plan provision” means any plan provision which— No pension plan to which section 1052 of this title applies may make effective any plan amendment with respect to breaks in service (which amendment is made or becomes effective after January 1, 1974, and before the date on which section 1052 of this title first becomes effective with respect to such plan) which provides that any employee’s participation in the plan would commence at any date later than the later of— No pension plan to which section 1053 of this title applies may make effective any plan amendment with respect to breaks in service (which amendment is made or becomes effective after January 1, 1974, and before the date on which section 1053 of this title first becomes effective with respect to such plan) if such amendment provides that the nonforfeitable benefit derived from employer contributions to which any employee would be entitled is less than the lesser of the nonforfeitable benefit derived from employer contributions to which he would be entitled under—