Car tax declaration UK — every vehicle keeper has ongoing legal obligations to notify DVLA of certain events. Failing to make the correct car tax declaration can result in penalties, back-payment demands, or prosecution. Here is what you must declare in 2026.

What Is a Car Tax Declaration?

A car tax declaration is any notification you make to DVLA that affects your vehicle's tax status. This includes registering a new vehicle, notifying a change of keeper (sale), declaring a SORN, notifying a vehicle's destruction (scrappage), and reporting significant modifications that change the vehicle's specifications.

The key principle is that your car tax declaration must always reflect the true state of the vehicle. Deliberately providing false information to DVLA is a criminal offence under the Vehicle Excise and Registration Act 1994.

When to Make a Car Tax Declaration

  • Buying a vehicle: Declare within 2 weeks of purchase using the V5C — tax is your responsibility from the date of purchase
  • Selling a vehicle: Declare immediately using the green slip from V5C — protects you from future liabilities
  • Taking vehicle off road: Declare SORN immediately — no road tax is due while SORN is active
  • Modifying the vehicle: Notify DVLA of any modification that changes engine type, fuel type, body style, or CO2 emissions
  • Changing address: Update V5C within 3 weeks of moving — road tax reminders go to your registered address
  • Scrapping a vehicle: Complete at an Authorised Treatment Facility — they notify DVLA electronically

Declaration of Vehicle Modifications

If you modify your vehicle in ways that affect its type approval or CO2 emissions, you must notify DVLA. Examples include converting a petrol engine to LPG (which changes the CO2 figure), converting any vehicle to electric power, changing the vehicle's body style, or fitting an engine from a different model with a different emissions rating.

DVLA may require a vehicle inspection before accepting the modification declaration. Failure to declare modifications can result in back-payment of underpaid VED.

Penalties for Incorrect Car Tax Declaration

Providing false information to DVLA is a criminal offence carrying fines of up to £5,000 and potential prosecution. Unintentional errors — such as failing to notify a modification — can be resolved voluntarily by contacting DVLA. The agency operates a voluntary disclosure process that reduces penalties for those who come forward before being caught.

Conclusion

Make a car tax declaration UK promptly for every vehicle status change — purchase, sale, SORN, modification. The V5C logbook is your primary tool. Visit GOV.UK notify DVLA of vehicle status for the complete declaration guide.