20 CFR §416.554

We will waive adjustment or recovery of an overpayment when an individual on whose behalf waiver is being considered is without fault (as defined in § 416.552) and adjustment or recovery would be against equity and good conscience. Adjustment or recovery is considered to be against equity and good conscience if an individual changed his or her position for the worse or relinquished a valuable right because of reliance upon a notice that payment would be made or because of the incorrect payment itself. In addition, adjustment or recovery is considered to be against equity and good conscience for an individual who is a member of an eligible couple that is legally separated and/or living apart for that part of an overpayment not received, but subject to recovery under § 416.570.