Tex. Tax Code § 154.301

(a) If the comptroller has reason to believe that a person has failed to pay a tax or penalty in the proper manner when due, as required by this chapter, or otherwise failed to comply with this chapter, the comptroller may employ auditors and investigators to determine compliance and any amount due. If the comptroller determines that the person has not paid the tax or penalty or has failed to comply with this chapter, the comptroller may require the person to pay the reasonable expenses incurred for the compliance investigation and audit as an additional penalty.

(b) The comptroller shall deposit funds paid under this section to the credit of the general revenue fund in the treasury to be used for making audits, conducting investigations, or as otherwise appropriated. The comptroller may use other funds available for audits as appropriated by the legislature.