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Bank Identification Number (BIN)
A bank identification number (BIN) is used to uniquely identify each bank or financial institution within the card networks. BINs are used to identify both issuers and acquirers.
Since cards can be issued by entities other than a bank — American Express, for example — issuer identification number (IIN) is often a more accurate term.
How Are BINs Used?
Merchants most commonly use BINs to identify the bank that issued a given card. They use this information to submit authorization requests and ensure payment settlements are routed to the correct institution. Merchants might also analyze chargeback data by BIN to determine which institutions process the most chargebacks — here is an example.
Check this blog article to learn more about BINs and how they can be used in risk management.
Major Industry Identifier (MII)
The first 4-8 digits of a cardholder’s account number reveal the issuer’s BIN. The first digit is called the major industry identifier (MII) and describes the issuer’s industry. The MII also helps identify the card association the issuer is a member of.
| MII Digit Value | Issuer Category | Card Brand |
| 0 | ISO/TC 68 and other industry assignments | None |
| 1 | Airlines | UATP |
| 2 | Airlines, financial, and other future industry assignments | MIR, Mastercard |
| 3 | Travel and entertainment | American Express, Diners Club Carte Blanche, Diners Club International, JCB |
| 4 | Banking and financial | Visa |
| 5 | Banking and financial | Mastercard, Diners Club US & Canada, Maestro, Dankort |
| 6 | Merchandising, banking, and financial | Discover, China UnionPay, InterPayment, InstaPayment |
| 7 | Petroleum and other future industry assignments | None |
| 8 | Healthcare, telecommunications, and other future industry assignments | None |
| 9 | Reserved for assignment by national standards organizations | N/A |