With the passing of Senate Bill 792 all applicants for disabled parking placards or plates with an ISA (International symbol of access) will be required to be medically certified. This includes renewals of existing placards and plates. You can do this by providing a completed and notarized VTR-214 or a prescription stating that the person is permanently disabled.
If you require additional forms, you may visit the Texas DMV Forms website and download the forms you need. You can apply online for AG and Timber exemptions through the Texas Comptroller's website.