20 CFR §219.65

1. (a)The Board may ask for a statement from an employer listing the annuitant's earnings by months and explaining any payments made to the annuitant when he or she was not working.
2. (b)The Board may ask for copies of award notices from a public agency showing the amounts of periodic payments and the period covered by each payment.
3. (c)The Board may ask for a statement from the applicant explaining discrepancies and may ask for sworn statements from persons who have personal knowledge of the facts or for any other convincing evidence.
4. (d)The Board may ask for proof of the court appointment of a legal representative, such as:
   1. (1)Certified copy of letters of appointment;
   2. (2)“Short” certificate;
   3. (3)Certified copy of order of appointment; or
   4. (4)Any official document issued by the clerk or other proper official of the appointing court.