If Social Security thinks that you got benefits when you were not supposed to get them, they must tell you in writing before they may take any money out of your check. You may appeal their decision.
You may appeal by filing SSA Form 561, “Request for Reconsideration.” You have 60 days from the date of the overpayment notice to make the request. If you do that within ten days of getting your notice, Social Security will not take any money out of your check until it makes a decision on your request.
You may also ask Social Security to waive the overpaid amount by filing SSA Form 632, “Request for Waiver of Overpayment Recovery or Change in Repayment.” You may ask this at any time, even after Social Security starts collecting the overpayment from you.
You can learn more about Social Security Overpayments in this article.