Tex. Tax Code § 162.502

(a) On or before the fifth workday after the end of each month, the comptroller, after making the deductions for refund purposes, shall determine as accurately as possible, for the period since the latest determination under this subsection, the number of gallons of fuel used in motorboats on which the gasoline tax has been paid to this state, on which refund of the tax has not been made, and against which limitation has run for filing claim for refund of the tax. From the number of gallons so determined the comptroller shall compute the amount of taxes that would have been refunded under the law had refund claims been filed in accordance with the law.

(b) The comptroller shall allocate and deposit these unclaimed refunds as follows:

(1) 25 percent of the revenues based on unclaimed refunds of taxes paid on motor fuel used in motorboats shall be deposited to the credit of the available school fund; and

(2) the remaining 75 percent of the revenue shall be deposited to the credit of the general revenue fund.

(c) Money deposited to the credit of the general revenue fund under Subsection (b)(2) may be appropriated only to the Parks and Wildlife Department for any lawful purpose.