Good morning Leo,
I'm Doug, and I'm very sorry to hear of your situation. My goal is to provide you with excellent service today. You posted your number, and in case you would like a phone conference with me, I will make a call offer to you after I post this answer.
Based on your statement of the facts it would appear that your daughter was receiving social security disability benefits based on her medical condition and yet took a job where she was earning in excess of the money allowed under social security rules and ended up receiving an overpayment letter for money paid that should not have been paid.
Under the present circumstances, you will need to file for a waiver of the overpayment based on the fact that you were unaware that your daughter was ineligible and that you are financially hurting, and paying it back would result in an extreme financial hardship on you, possibly resulting in your need to go on public assistance.
You can file for a waiver (it's a form SSA-632) and here is the link to the form:
You will want to indicate that the overpayment was in no way your fault, that the over payment was not made to you but to your adult daughter over whom you were not a legal guardian nor over whom did you exercise control, and that you cannot afford to repay the money they are asking for.
Alternatively, you may argue need. Recovery of an overpayment will defeat the purpose of Title II of the Social Security Act if recovery would deprive the beneficiary of income required for ordinary and necessary living expenses. POMS GN 02250.100; 20 C.F.R. § 404.508. Such ordinary living expenses can include: food, clothing, rent/mortgage, utilities, insurance premiums, taxes, medical expenses, and other miscellaneous expenses. Proof that recovery would deprive the person of such income can be shown on SSA's Request for Waiver form.
Just fill out the questions as they appear on the form. Then drop it off, or mail it to your local social security office.
Even if they don't approve your waiver, at least they will stop collection efforts until they decide on your waiver. If they deny your request for a waiver, you may appeal their decision two times. If the waiver is denied the first time, I would urge you to retain a local Social Security attorney to represent you on the appeals---to give you a better chance at persuading them to grant the waiver.
You may reply back to me using the Reply link and I will be happy to continue to assist you until I am able to address your concerns, to your satisfaction.
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I wish you and yours the best this holiday season,