Question: What if a voter doesn't have any one of the acceptable forms of ID?
Answer: If a voter does not have a permanent disability exemption (addressed below) indicated on his or her voter registration certificate OR the voter does not have any of the photo identifications indicated above at the time of voting,
the voter may cast a provisional ballot at the polls. However, in order to have the provisional ballot counted, the voter will be required to visit the voter registrar’s office within six (6) calendar days after the date of the election to either present one of the above forms of photo ID OR submit one of the temporary affidavits addressed below (e.g., religious objection or natural disaster) in the presence of the county voter registrar while attesting to the fact that he or she does not have any of the required photo IDs.
A permanent exemption is available for voters with documented disabilities. Voters with a disability may apply with the county voter registrar for a permanent exemption. The application must contain written documentation from either the U.S. Social Security Administration evidencing the applicant’s disability, or from the U.S. Department of Veterans Affairs evidencing a disability rating of at least 50 percent. In addition, the applicant must state that he or she has no valid form of photo identification. Those who obtain a disability exemption will be allowed to vote by presenting a voter registration certificate reflecting the exemption. The exemption is evidenced by a capital “E” appearing next to the Voter Unique Identifier (VUID) on the voter’s voter registration certificate.
Temporary exemptions are available for voters who have a consistent religious objection to being photographed and for voters who do not have any photo identification as a result of certain natural disasters as declared by the President of the United States or the Texas Governor within 45 days of the day the ballot was cast. A voter must present themselves to the voter registrar and execute the affidavit with the 6th day (sixth day) after election day in order to have their provisional ballot counted.
http://www.votetexas.gov/faq/