Tex. Transportation Code § 451.405: 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 to increase the rate of the authority's sales and use tax has no effect if:

(1) the voters of the authority approve the authority's sales and use tax rate or rate increase at an election held on the same day on which a municipality or county having territory within the authority adopts a sales and use tax or an additional sales and use tax; and

(2) the combined rates of all sales and use taxes imposed by the authority and other political subdivisions of the state would exceed two percent in any location in the authority.

Acts 1995, 74th Leg., ch. 165, Sec. 1, eff. Sept. 1, 1995.