Tex. Tax Code § 111.0511 - Restricted or Conditional Payments to Comptroller Prohibited

(a) In this section, "taxes" includes the tax and any penalties and interest relating to a tax liability.

(b) Unless the restriction or condition is authorized by this title, a restriction or condition placed on a check or other money instrument in payment of taxes by the maker that purports to limit the amount of taxes owed or place a condition on its acceptance or negotiation is void.