29 U.S.C. § 1161: Plans must provide continuation coverage to certain individuals

The plan sponsor of each group health plan shall provide, in accordance with this part, that each qualified beneficiary who would lose coverage under the plan as a result of a qualifying event is entitled, under the plan, to elect, within the election period, continuation coverage under the plan. Subsection (a) shall not apply to any group health plan for any calendar year if all employers maintaining such plan normally employed fewer than 20 employees on a typical business day during the preceding calendar year. The amendments made by this section [enacting this part and amending section 1132 of this title ] shall apply to plan years beginning on or after July 1, 1986 . the date on which the last of the collective bargaining agreements relating to the plan terminates (determined without regard to any extension thereof agreed to after the date of the enactment of this Act), or January 1, 1987 .