29 USC 1163 – Qualifying event
For purposes of this part, the term “qualifying event” means, with respect to any covered employee, any of the following events which, but for the continuation coverage required under this part, would result in the loss of coverage of a qualified beneficiary:
(1) The death of the covered employee.
(2) The termination (other than by reason of such employee’s gross misconduct), or reduction of hours, of the covered employee’s employment.
(3) The divorce or legal separation of the covered employee from the employee’s spouse.
(4) The covered employee becoming entitled to benefits under title XVIII of the Social Security Act [42 U.S.C. 1395 et seq.].
(5) A dependent child ceasing to be a dependent child under the generally applicable requirements of the plan.
(6) A proceeding in a case under title 11, commencing on or after July 1, 1986, with respect to the employer from whose employment the covered employee retired at any time.
In the case of an event described in paragraph (6), a loss of coverage includes a substantial elimination of coverage with respect to a qualified beneficiary described in section 1167(3)(C) of this title within one year before or after the date of commencement of the proceeding.