Your letter must include your name, address, Social Security number, and why you disagree with the determination. Select Benefit Overpayment Services.Select Make a Payment. The salary overpayment resulted because . We have identified the following overpayment and are in good faith voluntarily refunding all monies collected in error. 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. An overpayment is any amount of any aid payment an AU received to which it was not eligible. An overpayment may be all or a portion of an aid payment.