20 CFR §217.11

1. (a)An applicant has “good cause” for a delay in the filing of an application for a lump-sum death payment or an annuity unpaid at death, as shown in § 217.9(c)(1) and (2), if the delay was due to—
   1. (1)Circumstances beyond the applicant's control, such as extended illiness, mental or physical incapacity, or communication difficulties; or
   2. (2)Incorrect or incomplete information furnished by the Board; or
   3. (3)Efforts by the applicant to secure evidence without realizing that evidence could be submitted after filing an application; or
   4. (4)Unusual or unavoidable circumstances which show that the applicant could not reasonably be expected to have been aware of the need to file an application within the set time limit.
2. (b)An applicant does not have good cause for a delay in filing if he or she was informed of the need to file within the set time limit but neglected to do so or decided not to file.