Texas Tax Code - TAX § 111.061. Penalty on Delinquent Tax or Tax Reports

(a) Except as otherwise provided, a penalty of five percent of the tax due shall be imposed on a person who fails to pay a tax imposed or file a report required by Title 2 or 3 of this code  1 when due, and, if the person fails to file the report or pay the tax within 30 days after the day on which the tax or report is due, an additional five percent penalty shall be imposed.

(b) Except where another penalty for fraud or intent to evade the tax is specifically provided, an additional penalty of 50 percent of the tax due shall be imposed if it is determined that:

(c) The penalties provided by Subsection (b) are intended to be remedial in nature and are provided for the protection of state revenue and to reimburse the state for expenses incurred as a result of fraud, including expenses incurred in conducting an investigation.