If you have an overpayment, we'll send you a decision letter. It will say how much you owe.Client's Name and Address: Provide the client's name and address as it appears in payment system. 2. Date: Enter the date that the DSHS 18-398 is filled out. 3. Use this sample letter. Send your letter so that it reaches the issuer within 60 days after the first bill with the error was sent to you. Complete this form if any of the following applies: You think that you are not at fault for the overpayment and you cannot afford to pay the money back. What should I do if Social Security says I was overpaid? You have to tell your credit or debit card company about any error you're disputing within 60 days of when the first statement with the charge was sent to you.