SORN reference numbers: 11-digit, 12-digit and 16-digit

DVLA uses several reference numbers, and using the wrong one is the most common reason the online SORN service says "not recognised". Here's which is which.

Checked against GOV.UK guidance · Updated 25 October 2026

The three numbers at a glance

GOV.UK's Make a SORN service accepts the 11-digit V5C reference and the 16-digit reminder reference. The Tax your vehicle service accepts those and the reference on the green new keeper slip.

The 11-digit V5C document reference

This identifies your current log book. Every time DVLA issues a new V5C (for example after a change of address or keeper), a new reference is created and the old one stops working. If the online service rejects your 11-digit number, check that you're holding the latest log book.

The 16-digit tax reminder reference

DVLA sends reminders before tax runs out. The reference on the reminder works for SORN too, which is handy if your log book is lost or with someone else. Reminders and "last chance" letters are often the quickest way to sort things out.

The 12-digit new keeper slip (V5C/2)

When you buy a vehicle, the seller should give you the green new keeper slip. You can use it to tax the vehicle straight away. To SORN a vehicle you've just bought, you'll generally need to wait for your own V5C to arrive (a new log book usually arrives within a few weeks of the change of keeper being recorded), then SORN with its 11-digit reference. Alternatively use SORN by post. The previous keeper's SORN does not carry over to you. See bought a car with SORN.

Numbers you can't use

• the registration number (number plate) on its own
• the VIN (chassis number)
• the old keeper's V5C reference after the vehicle has changed hands
• an MOT test number

Can't find any reference?

Follow our guide to SORN without a V5C, or call DVLA Vehicle Enquiries on 0300 790 6802 (all contact numbers).