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.This memorandum serves as notification of an overpayment of wages that you received and the subsequent repayment that is your responsibility. 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.