Irish and British banks use sort codes, along with account numbers, for routing domestic money transfers from bank to bank, and these sort codes are comparable to the routing numbers that banks in the United States use. Banks generally use different sort codes for different types of accounts, and there may be multiple sort codes used for one account category. For example, the bank Nationwide has four sort codes for current accounts as of January 2015.
A modern sort code has six digits, with three sets of two digits separated by hyphens. The first two digits of the code identifies the bank, and each bank is assigned a specific range of numbers to use. While a sort code is used for domestic transfers, a different bank identifier code is used for international transfers.