Doctor Who star David Tennant has allegedly been spotted driving with an expired car tax disc.

We show you how to save money on road tax and what happens if you fail to tax your vehicle.

David Tennant was apparently seen driving with an out-of-date tax disc last month, after leaving a Radio Times party in London, according to The Sun.

The newspaper reported the 37-year-old actor – who is well-known for his role as TV’s Doctor Who – was unaware of the expired disc.

Tennant’s Toyota Prius was still sporting the tax disc almost three weeks after it expired – on New Year’s Eve.

Other celebrity mishaps include Wayne Rooney filling up with the wrong fuel and Princess Beatrice leaving her car unlocked with keys in the ignition.

What happens if you don’t tax your car?

If your vehicle is spotted without a valid tax disc or reported unpaid from a DVLA record check, this could result in:

• An £80 penalty
• A minimum £1,000 fine
• Your car being clamped and towed
• Your car being impounded and crushed
• A £5,000 fine and two-years imprisonment for falsely declaring Statutory Off Road Notification (SORN). SORN allows you to keep your car off the road for up to a year.

The DVLA works with the police and local authorities to spot untaxed cars. They use automatic number plate readers (ANPR) to identify, clamp and tow away untaxed vehicles on public roads.

How to tax your car

Visit the DVLA’s tax disc website and follow the instructions or call 0845 850 4444.

To find out how much your car costs to tax read our 2009 road tax guide.

Money-saving tax tips

1. Buy annually rather than every six months and save up to £40
2. Pay for your car tax online and save postage fees
3. Go green – buy a green car which emits less CO2 and costs less to tax
4. Buy a car registered before 1 January 1973 and you won’t have to pay a penny in tax. Bear in mind it’s unlikely to have power steering, electric windows and other in-car comforts
5. Drive an alternative fuel car and save at least £20 per tax band

View all of the UK’s tax-free cars:

View footage of the Toyota Prius:

How much will it cost to tax YOUR car?