Tex. Tax Code § 111.104

(a) If the comptroller finds that an amount of tax, penalty, or interest has been unlawfully or erroneously collected, the comptroller shall credit the amount against any other amount when due and payable by the taxpayer from whom the amount was collected. The remainder of the amount, if any, may be refunded to the taxpayer from money appropriated for tax refund purposes.

(b) A tax refund claim may be filed with the comptroller only by the person who directly paid the tax to this state or by the person's attorney, assignee, or other successor.

(c) A claim for a refund must:

(1) be written;

(2) state fully and in detail each reason or ground on which the claim is founded; and

(3) be filed before the expiration of the applicable limitation period as provided by this code or before the expiration of six months after a jeopardy or deficiency determination becomes final, whichever period expires later.

(d) A refund claim for an amount of tax that has been found due in a jeopardy or deficiency determination is limited to the amount of tax, penalty, and interest and to the tax payment period for which the determination was issued. The failure to file a timely tax refund claim is a waiver of any demand against the state for an alleged overpayment.

(e) This section applies to all taxes and license fees collected or administered by the comptroller, except the state property tax.

(f) No taxes, penalties, or interest may be refunded to a person who has collected the taxes from another person unless the person has refunded all the taxes and interest to the person from whom the taxes were collected.