Issuer Identification Number (IIN)

DEFINITION of 'Issuer Identification Number (IIN)'

A numbering system that allows a credit, debit, or other card to be identified as having been issued by a particular financial institution. The issuer identification number (IIN) is a six digit number that is unique to a single card issuer. The number is only used to identify the card issuer, and is not used to identify a particular product, service, or region associated with the card issuer.

BREAKING DOWN 'Issuer Identification Number (IIN)'

Every time a card is used in a transaction a card processor goes through a series of verification steps to ensure that the cardholder is authorized to make the transaction, and that the account has sufficient funds. The number found on the front of the credit card is not a randomly assigned number; instead, the digits represent a code that identifies not only the cardholder but also the card issuer.

The number of digits on the front of the credit card may vary according to the needs of the card issuer – typically 13 to 16 digits - but all cards include an issuer identification number (IIN) that is specific to the card issuer. Each card issuer is only allowed to have one IIN. This means that the issuer must ensure that all of its products, services, and geographic-specific information can be identified through the IIN

The issuer identification number is found in the first six digits of a card number. The remaining digits on the card i.e. digits 7 through 16 are used to identify the cardholder. This is called the customer account number or primary account number.

When a credit card is swiped at a terminal or used on a website, the transaction process includes looking up the IIN in order to validate the transaction. The validation process may include a review of the location of the card issuing company compared to the location of the cardholder’s billing address. This validation typically employs an algorithm, such as the Luhn algorithm, that sums up the card’s digits.