29 CFR 4003.5: Non-timely request for review.

PBGC will process a request for review of an initial determination that was not filed within the prescribed period of time for requesting review (see §§ 4003.32 and 4003.52) if—

(a) The person requesting review demonstrates in his or her request that he or she did not file a timely request for review because he or she neither knew nor, with due diligence, could have known of the initial determination; and

(b) The request for review is filed within 30 days after the date the aggrieved person, exercising due diligence at all relevant times, first learned of the initial determination where the requested review is reconsideration, or within 45 days after the date the aggrieved person, exercising due diligence at all relevant times, first learned of the initial determination where the request for review is an appeal.