VIN & V5C
V5C document reference number
11-digit number on the top right of the V5C. Required for online tax, transfers and HPI-style checks.
The DVLA issues a new reference number every time a V5C is reprinted. A vehicle data check returns whether the supplied number matches the DVLA's current record. A mismatch — for example, the seller's V5C number is not the latest one on file — suggests the document is a duplicate, lost, or forged.