Tex. Elec. Code § 501.1035

A municipality that includes an area annexed to the municipality on or after the date on which a petition requesting a local option election in the municipality is filed may hold the election in the municipality only if the petition contains a sufficient number of signatures to meet the requirements of Section 501.032, based on the number of qualified voters in the municipality, including the annexed area. The qualified voters of the annexed area must be allowed to vote in the local option election. The results of the election shall determine the local option status of the municipality, including the annexed area.