20 C.F.R. § 416.558

(a) Notice of overpayment and underpayment determination. Whenever a determination concerning the amount paid and payable for any period is made and it is found that, with respect to any month in the period, more or less than the correct amount was paid, written notice of the correct and incorrect amounts for each such month in the period will be sent to the individual against whom adjustment or recovery of the overpayment as defined in § 416.537(a) may be effected or to whom the underpayment as defined in §§ 416.536 and any amounts subject to installment payments as defined in § 416.544 would be payable, notwithstanding the fact that part or all of the underpayment must be withheld in accordance with § 416.543. When notifying an individual of a determination of overpayment, the Social Security Administration will, in the notice, also advise the individual that adjustment or recovery is required, as set forth in § 416.571, except under certain specified conditions, and of his or her right to request waiver of adjustment or recovery of the overpayment under the provisions of § 416.550.

(b) Notice of waiver determination. Written notice of an initial determination of waiver shall be given the individual in accordance with § 416.1404 unless the individual was not given notice of the overpayment in accordance with paragraph (a) of this section.