Tex. Transportation Code § 451.706

(a) The combined rate of all sales and use taxes imposed by the district and all other political subdivisions of this state may not exceed two percent in any location in the district.

(b) If the approval of the district's tax at an election held under Section 451.705 would cause the tax in a political subdivision to exceed the limit imposed under Subsection (a), the governing body of the political subdivision holding an election under Section 451.705 shall prepare the ballot to allow the voters of the subdivision to determine which portion of other sales taxes of that subdivision will be repealed if the voters approve joining the district, except that the following may not be reduced:

(1) the sales and use tax of the authority; and

(2) a sales and use tax of not more than one percent imposed by a municipality under Section 321.101(a) or 321.103(a), Tax Code.

(c) The sales and use tax authorized by this subchapter and the repeal of any local sales and use taxes under this section take effect on the first day of the second calendar quarter beginning after the date the comptroller receives a copy of the order canvassing the results of the election.

(d) At an election held under Subsection (b), the ballot shall be prepared to permit voting for or against substantially the following proposition: "Joining the Advanced Transportation District, authorizing a sales and use tax at the rate of ___ (rate imposed elsewhere in the district), and repealing ____ cents of the following sales and use taxes used for ___________________________." Not later than the 45th day before the election date, the governing body of the political subdivision shall submit the ballot language to the authority for approval.