31 C.F.R. § 29.522
(a) General rule. A debtor is considered to be at fault if he or she, or any other person having an interest in obtaining a waiver of the claim, caused or contributed to the accrual of the overpayment. The Department considers a debtor or any other person having an interest in obtaining a waiver of the claim to have caused or contributed to the accrual of an overpayment if—
(3) The following factors may affect the decision as to whether the debtor is or is not at fault where the debtor submitted an incorrect statement, or the debtor failed to disclose material facts in his or her possession—
(b) Knowledge of an overpayment.