TEXAS WRITE IN CANDIDATE REQUIREMENTS§ 146.022. CANDIDATE'S NAME REQUIRED TO APPEAR ON LIST. A write-in vote may not be counted unless the name written in appears on the list of write-in candidates required by Section 146.031.
§ 146.031. LIST OF WRITE-IN CANDIDATES.
(a) The authority responsible for having the official ballot prepared shall prepare a list containing the name of each write-in candidate certified to the authority. Each name must appear in the form in which it is certified.
(b) A write-in candidate's name may not appear more than once on the list.
(c) Copies of the list shall be distributed to the counting officers in the election for use in counting write-in votes.
(d) Copies of the list shall be distributed to each presiding election judge with the other election supplies. A copy of the list shall be posted in each polling place at each place where an instruction poster is required to be posted.
(e) The authority responsible for having the official ballot prepared shall retain a copy of the list and preserve it for the period for preserving the precinct election records.
... Go to the above link for full code requirements...
Declaration or write in Candidate Form
Fee, etc.