Customers needing assistance with their unemployment insurance claim should contact us via phone at 888-737-0259. An overpayment occurs when you are paid unemployment insurance benefits you are not entitled to receive.Our document template is designed to make the process of writing an "Inform a Customer of an Overpayment" letter quick, easy, and stress-free. To pay an overpayment, you can agree to pay the amount in monthly installments. Usually, DSS will ask you to pay off the overpayment in one year. This brief but important letter notifies a customer that he or she has overpaid you. It can serve as a very good customer relations letter.