In the UK they continue to be used to route transactions domestically within clearance organizations and to identify accounts, while in the Republic of Ireland (a founder member of the Euro) they have been deprecated and replaced by the Single European Payment Area (SEPA) systems and infrastructure.
Six-digit "sorting codes" were introduced in a staggered process from 1957 as the banking industry moved towards automation.
The national codes were retained but where a single digit was used to identify the bank a two-digit range was introduced.
In the following list the dates in parentheses give the year of merger with the present-day sort code holder, or its subsidiary.
Sort codes are no longer directly used in the Republic of Ireland, although they still form part of the underlying structure of account numbers.
This means that all domestic transactions, including Direct Debit and interbank transfers, are processed using an IBAN through the SEPA system.
Codes are issued by the Banking and Payments Federation Ireland (BPFI)[8] which replaced IPSO in 2014.
Individual sort codes were allocated on a one-off basis to the many London offices of private and foreign banks.
Transfers to and from the United Kingdom, the United States and Australia and any other countries outside the Eurozone continue to use international networks and require a combination of IBAN (or a domestic account and sorting/routing code) alongside a BIC code to identify the institution sending and receiving payments.
Characters 9 to 14 of British and Irish IBANs hold the bank account sort code.
Examples include: The codes listed above for Germany, Austria, Switzerland and Sweden are incorporated into the IBANs for those countries.