Texas Election Code - ELEC § 146.054. Filing Deadline

(a) Except as provided by Subsection (b), a declaration of write-in candidacy must be filed not later than 5 p.m. of the fifth day after the date an application for a place on the ballot is required to be filed.

(b) For an election to be held on a uniform election date, the day of the filing deadline is the 74th day before election day.

(c) A write-in candidate may not withdraw from the election after the 71st day before election day.