Tex. Tax Code § 151.423

A taxpayer may deduct and withhold one-half of one percent of the amount of taxes due from the taxpayer on a timely return as reimbursement for the cost of collecting the taxes imposed by this chapter. The comptroller shall provide a card with each form distributed for the collection of taxes under this chapter. The card may be inserted by the taxpayer with the tax payment to provide for contribution of all or part of the reimbursement provided by this section for use as grants under Subchapter M, Chapter 56, Education Code. If the taxpayer chooses to contribute the reimbursement for the grants, the taxpayer shall include the amount of the reimbursement contribution with the tax payment. The comptroller shall transfer money contributed under this section for grants under Subchapter M, Chapter 56, Education Code, to the appropriate fund.