Sort code
The six-digit code, written 12-34-56, that tells you which British bank – and often which branch – an account belongs to.
The code dates from the era of paper cheque clearing, when it literally decided which pile a cheque landed on. The leading digits identify the bank, the rest the branch. Paired with an eight-digit account number it is still how Britons give out their bank details, and it sits inside the UK BBAN portion of an IBAN. The registry, the Extended Industry Sort Code Directory, also records which schemes each code can be reached through: Bacs, Faster Payments, CHAPS.
Validation follows a published modulus-checking specification in which the weighting depends on the sort code – and where some banks have exceptions to the exceptions. Nor does the code say anything about who owns the account, which is why the UK built Confirmation of Payee.