You can tax your car starting from the 5th day in the month where you current tax disc would expire. So if your tax disc expires on the 23rd of March, you can tax it as early as the 5th of March or any date after that. You can also renew your tax disc 2 months in advance of the expiration date if you're going abroad for a longer time. However you can only do that at a Post Office which deals with advance applications or at your local DVLA office.
If you're considering getting the tax sorted 2 months before it runs out, you will have to do it either in person or by post and will need to have the following documents:
- Valid MOT certificate (must be valid when the new tax disc starts)
- Valid insurance (must be valid when the new tax disc starts)
- Registration certificate
- V10 application must be filled in (Vehicle Licence Application)
- Letter justifying the advance taxing if you're making application through the post
If you're taxing your car in the same month that the current tax disc expires, you can do it by phone or online as well. For more information, please refer to DirectGov Vehicle Taxing.