Some disabled people can get Exemption of VED for one car. You, or someone you nominate, may have a free ‘tax disc' if you get:
If you get the standard rate mobility component of PIP, you may be entitled to 50% off your VED. When you are awarded your qualifying benefit, you should be sent a re-usable Certificate of Entitlement. You'll need this each time you renew your VED. Even if you have a certificate, the DVLA can refuse to grant an exemption if they think the vehicle will not be used solely by or for the purposes of the disabled person.
Hope this helps - let us know if you have any further questions