In the United Kingdom, a driving licence number is a unique 16 or 18-character code that is a mixture of letters and numbers. It is unique to the driver and can be found on the front of the photocard driving licence. The driver number is made up of the following components:

• Surname: The first five characters of the drivers surname. If the surname is less than five characters, the remaining spaces are filled with the number 9. If the surname is longer, only the first five letters are used.

• Date of birth: Six characters that represent the drivers date of birth. The first and last numbers are the year of birth. The second and third numbers are the month of birth. For female drivers, the second digit is incremented by 5, so it will be 5 or 6. The fourth and fifth digits are the day of the month of birth.

• Initials: The first two initials of the drivers first names. If the driver has no middle name, the character is replaced with a 9.

• Random security numbers: The last three characters are randomised for additional security. This helps stop fraudsters guessing the driving licence number based on the drivers name and date of birth only.

• Computer check digits: Two computer-generated check digits that are used to verify the accuracy of the driver number.

• Licence issue number: This is a two-digit number that represents the number of times the driver has been issued a UK driving licence. It is not part of the 16-digit driving licence number, even though its on the same part of the licence.

It is important to note that driver numbers in Northern Ireland differ from those issued to drivers in Great Britain. Each Northern Ireland licence holder is assigned a unique, 8-digit driving licence number, which is assigned randomly and in no specific order.