Overpayment Information. If you have received an overpayment notice from DETR, you may be required to repay the excess amount.1) Pay the overpayment in full. In order for an overpayment refund to be processed in a timely manner, please submit a completed form with all refund checks and supporting documentation. The salary overpayment resulted because . This chapter deals with state law provisions identifying, establishing, and collecting overpayments. All states have provisions addressing these matters. 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. Discover each state's laws related to insurance overpayment recovery and feel confident in your process managing overpayments and credit balances.