29 U.S.C. § 1061: Effective dates

Except as otherwise provided in this section, this part shall apply in the case of plan years beginning after September 2, 1974 . Except as otherwise provided in subsection (d), sections 1055, 1056(d) and 1058 of this title shall apply with respect to plan years beginning after December 31, 1975 . Except as otherwise provided in subsections (c) and (d) in the case of a plan in existence on January 1, 1974 , this part shall apply in the case of plan years beginning after December 31, 1975 . the date on which the last of such agreements relating to the plan terminates (determined without regard to any extension thereof agreed to after September 2, 1974 ), or December 31, 1980 . provides supplementary benefits, not in excess of one-third of the basic benefit, in the form of an annuity for the life of the participant, or provides that, under a contractual agreement based on medical evidence as to the effects of working in an adverse environment for an extended period of time, a participant having 25 years of service is to be treated as having 30 years of service. This subsection shall apply with respect to a plan if (and only if) the application of this subsection results in a later effective date for this part than the effective date required by subsection (b). If the administrator of a plan elects under section 1017(d) of this Act to make applicable to a plan year and to all subsequent plan years the provisions of title 26 relating to participation, vesting, funding, and form of benefit, this part shall apply to the first plan year to which such election applies and to all subsequent plan years. the date on which his participation would commence under the break in service rules of section 1052(b) of this title , or the date on which his participation would commence under the plan as in effect on January 1, 1974 . the break in service rules of section 1052(b)(3) of this title , or the plan as in effect on January 1, 1974 . The preceding provisions of this section shall not apply with respect to amendments made to this part in provisions enacted after September 2, 1974 .