What is an 'Issuer Identification Number (IIN)'

The issuer identification number (IIN) is the first few digits of a payment card number issued by a financial institution. The issuer identification number is unique to the issuer and their partnering network provider. It helps to identify the processing network used for the card’s transactions.

BREAKING DOWN 'Issuer Identification Number (IIN)'

The issuer identification number is the first few digits of a string of numbers created to provide a unique payment card identifier for customers. The numbering system allows a credit, debit or other payment card to be identified as having been issued through a processing network by a financial institution. The number is only used to identify the card network, and is not used to identify a particular product, service, or region associated with the card issuer.

Common Issuer Identification Numbers

When issuing a customer a payment card, the issuer will create a unique identifier that is used for record keeping and transaction processing. Payment card numbers can vary in length but are usually comprised of 16 digits.

The first few digits of a payment card are the issuer identification number and provide details on the processing network. These digits can range from one to six with issuers having established unique issuer identification numbers for which they are recognized in the industry. Examples of issuer identification numbers include the following:

American Express: 34, 37

Discover Card: 6011, 64, 65

Mastercard: 2221 to 2720, 51 to 55

Visa: 4

Payment Card Numbers

Financial institutions issue payment card numbers with debit, credit and other types of cards. 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 card is not a randomly assigned number; instead, the digits represent a code that identifies the cardholder and links it with the financial institution issuing the card.

The number of digits on the front of a card may vary and are typically 12 to 16 digits. The first few digits represent the issuer identification number. The remaining digits on the card are used to identify the cardholder and link it to a particular account with a financial institution. Payment card numbers are unique identifiers that are different than a customer’s primary account number. A payment card number is an additional identifier that is also associated with a customer’s account. Each time a customer is issued a new type of payment card it will have its own unique payment card number.

A payment card number is used when processing a transaction. When a card is swiped at a terminal or used on a website, the transaction process includes verification of the IIN as well as the payment card number. The payment card number provides a way for processing systems to communicate with a financial institution in order to ensure that the requested funds are available in the account. With the payment card number a verification system can access the location of the card issuing company, the cardholder’s billing address and the funds available for use.

Financial institution’s also track a customer’s transactions by their payment card number. The payment card number is the primary identifier associated with an account. It is linked to the fund’s in a customer’s account and associated with all types of charges that affect the account balance.

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