Are there different versions of the Texas Accessibility Standards? And which version should I use?

Yes, per these guidelines:

• the date you register the project with TDLR. (Local jurisdictions are required by State law to verify that projects have been registered with TDLR.); or
• the start of physical construction or alteration, if no building permit is required

If the date above is on or after April 1, 1994, and before March 15, 2012, the 1994 TAS would have governed the construction or alterations.

(Current version) If the date described above is on or after March 15, 2012, then all new construction or alterations must comply with the 2012 TAS.

The 2022 TAS is scheduled for release in 2023. Actual date to be announced.