There is no form to cancel a Statutory Off Road Notification and no button marked unSORN. The declaration ends by being replaced: the moment the vehicle is taxed, the SORN stops. That is the whole mechanism, and the reason people search for something more complicated is that the DVLA never advertises it as a cancellation, so it does not sound like the answer it is.
What actually ends a SORN
Tax the vehicle. Use the reference number from the V5C, the V11 reminder or the green new keeper slip, pay for the period you want, and the SORN ends on the day the tax starts. You do not need to tell DVLA separately, there is no cancellation form, and there is nothing to wait for beyond the transaction completing. Check the vehicle enquiry afterwards and confirm the status reads taxed, because the confirmation is what turns an intention into a record.
Insurance and an MOT have to be in place first
You cannot tax a vehicle without a valid MOT where one is required, and a vehicle coming back onto the road must be insured from the moment it is on the road. That creates the one genuinely awkward step: driving a SORN vehicle to a pre booked MOT appointment is permitted, and doing anything else with it on a public road is not. Book the test, insure the car, drive it to the appointment, then tax it once it has passed.
A SORN does not travel with the car
When a vehicle changes keeper the existing SORN ends, and the new keeper must either tax it or make their own declaration. A buyer who assumes the seller's SORN still covers them has an untaxed vehicle in their name from the day of purchase. This is the same rule as vehicle tax, which is also cancelled at the keeper change and refunded to the seller, and it catches out private buyers every week.
If you are not putting it back on the road yet
The SORN continues indefinitely while the vehicle is kept off the public road, so there is nothing to renew and nothing to do. What matters is where the vehicle is: a driveway, a garage or private land is fine, and the road outside your house is not, whatever the surface looks like. If the vehicle is going to be scrapped instead, the notification to DVLA is a different transaction and is the one that actually takes it off the register.
Questions people ask about how to unsorn a car
Is there a form to cancel a SORN?
No. Taxing the vehicle ends the SORN automatically, and that is the only route. There is no separate cancellation transaction to complete.
Can I drive a SORN car to its MOT?
Yes, to a pre booked test, and the vehicle still needs to be insured. Any other use on a public road while the SORN is in force is not permitted.
Does a SORN transfer to the new owner?
No. It ends at the keeper change. The new keeper taxes the vehicle or makes their own declaration, and until one of those happens the vehicle is untaxed in their name.
How do I confirm the SORN has ended?
Run the free DVLA vehicle enquiry on the registration. It reports tax status and SORN status, so a taxed reading with no SORN is the confirmation.