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.Our document template is designed to make the process of writing an "Inform a Customer of an Overpayment" letter quick, easy, and stress-free. The salary overpayment resulted because . A statement or letter from the company indicating: (1) Property Index Number, (2) taxpayer's name,. Write a letter to the Social Security Administration. Tell them how much you can afford to pay each month. This memorandum serves as notification of an overpayment of wages that you received and the subsequent repayment that is your responsibility.