Section 16.003 - Late Payment Penalty(a) An additional fee equal to 10 percent of the amount due shall be assessed for any late payment of an assessment required under this subchapter.(b) An assessment delinquent for more than 30 days accrues interest at an annual rate of 12 percent on the amount of the assessment and penalty due. Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. Sept. 1, 1997.