Texas Family Code - FAM § 154.012. Support Paid in Excess of Support Order

(a) If an obligor is not in arrears and the obligor's child support obligation has terminated, the obligee shall return to the obligor a child support payment made by the obligor that exceeds the amount of support ordered, regardless of whether the payment was made before, on, or after the date the child support obligation terminated.

(b) An obligor may file a suit to recover a child support payment under Subsection (a). If the court finds that the obligee failed to return a child support payment under Subsection (a), the court shall order the obligee to pay to the obligor attorney's fees and all court costs in addition to the amount of support paid after the date the child support order terminated. For good cause shown, the court may waive the requirement that the obligee pay attorney's fees and costs if the court states the reasons supporting that finding.