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.The salary overpayment resulted because . We have identified the following overpayment and are in good faith voluntarily refunding all monies collected in error. This memorandum serves as notification of an overpayment of wages that you received and the subsequent repayment that is your responsibility. How do I request a refund? A. Fill out the Business Tax Refund Request form to request a refund from the City for an overpayment.