Texas Transportation Code - TRANSP § 452.403. Maximum Tax Rate in Authority Area

(a) An authority may not adopt a sales and use tax rate, including a rate increase, that when combined with the rates of all sales and use taxes imposed by other political subdivisions of the state having territory in the authority exceeds two percent in any location in the authority.

(b) An election by an authority to adopt a sales and use tax or increase the rate of the authority's sales and use tax has no effect if:

(c) If an authority consisting of one subregion governed by a subregional board created under Subchapter O  1 adds territory that is a municipality, any additional sales and use tax under Chapter 321, Tax Code, imposed by that municipality is repealed as provided by Section 321.1025, Tax Code. The effective date of the repeal and for the imposition of the tax authorized to be collected under Section 452.401 in the added territory is the date that, under Section 321.102(b), Tax Code, the repeal of the additional sales and use tax is effective in the territory.