(a) If a suit under this subchapter results in a final determination that all or part of the money paid under protest was unlawfully demanded by the public official and belongs to the taxpayer, the comptroller shall credit the proper amount, with the pro rata interest earned on that amount, against any other amount finally determined to be due to the state from the taxpayer according to information in the custody of the comptroller and shall refund the remainder by the issuance of a refund warrant.
(b) A refund warrant shall be written and signed by the comptroller.

(c) Each refund warrant shall be drawn against the accounts or funds to which the amounts paid under protest are allocated by law. If there are not sufficient funds in an account or fund to pay a refund required to be paid under Subsection (a), the comptroller shall draw the warrant against the General Revenue Fund or other account or fund from which refunds may be made, as the comptroller determines appropriate.
(d) The comptroller shall issue each refund warrant and shall deliver it to the person entitled to receive it.
(e) The comptroller may not refund an amount of tax to a taxpayer or person who collects taxes from another person unless the taxpayer or person refunds all the taxes to the person from whom the taxes were collected.