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.Providers have the option to submit a Request For Extended Repayment Schedule (ERS). A complete ERS request should be submitted immediately. The salary overpayment resulted because . This form is used when there has been an improper payment to the correct provider. Use our free Refund Demand Letter template to request the return of a payment. If we have identified an overpayment and request a refund, please mail the check along with a copy of the overpayment request letter we sent you.