29 C.F.R. § 4022.5

(a) A guaranteed benefit payable to a surviving beneficiary is not considered to be forfeitable solely because the plan provides that the benefit will cease upon the remarriage of such beneficiary or his attaining a specified age. However, the PBGC will observe the provisions of the plan relating to the effect of such remarriage or attainment of such specified age on the surviving beneficiary's eligibility to continue to receive benefit payments.

(b) Any other provision in a plan that the right to a benefit in pay status will cease or be suspended upon the occurrence of any specified condition does not automatically make that benefit forfeitable. In each such case the PBGC will determine whether the benefit is forfeitable.

(c) A benefit guaranteed under § 4022.6 shall not be considered forfeitable solely because the plan provides that upon recovery of the participant the benefit will cease.