Tex. Tax Code § 111.064

(a) Except as otherwise provided by this section, for a refund under this chapter, interest is at the rate that is the lesser of the annual rate of interest earned on deposits in the state treasury during November of the previous calendar year, as determined by the comptroller, or the rate set in Section 111.060, and accrues on the amount found to be erroneously paid for a period:

(1) beginning on the later of 60 days after the date of payment or the due date of the tax report; and

(2) ending on, as determined by the comptroller, either the date of allowance of credit on account of the comptroller's final decision or audit or a date not more than 10 days before the date of the refund warrant.

(b) A credit taken by a taxpayer on the taxpayer's return does not accrue interest.

(c) For a refund claimed before September 1, 2005, and granted for a report period due on or after January 1, 2000, the rate of interest is the rate set in Section 111.060.

(c-1) A refund, without regard to the date claimed, for a report period due before January 1, 2000, does not accrue interest.

(d) This section does not apply to an amount paid to the comptroller under Title 6, Property Code, or under an agreement made under Section 162.003.

(e) All warrants for interest payments shall be drawn against the fund or account into which the erroneously paid tax was deposited. The interest shall be paid from funds appropriated for that purpose.

(f) A local revenue fund is not subject to Subsections (a)-(c-1). In this subsection, "local revenue fund" includes a court cost, a fee, a fine, or a similar charge collected by a municipality, a county, or a court of this state and remitted to the comptroller.