The Tax Office holds unclaimed property tax overpayments made within the last three years and outstanding (uncashed) refund checks. 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. I'd personally let them know and refund the difference. Discuss the discrepancy, provide supporting evidence, and seek clarification on the payment amount. Child Support Attorney Houston - What if I overpay my child support obligations? The salary overpayment resulted because .