Texas Health and Safety Code - HEALTH & SAFETY § 486.031. Remittance of Penalty and Interest

(a) If the person paid the penalty and if the amount of the penalty is reduced or the penalty is not upheld by the court, the court shall order, when the court's judgment becomes final, that the appropriate amount plus accrued interest be remitted to the person before the 31st day after the date that the judgment of the court becomes final.

(b) The interest accrues at the rate charged on loans to depository institutions by the New York Federal Reserve Bank.

(c) The interest shall be paid for the period beginning on the date the penalty is paid and ending on the date the penalty is remitted.