Prefixes

The card number's prefix is the sequence of digits at the beginning of the number that determine the credit card network to which the number belongs. The first 6 digits of the credit card number are known as the Bank Identification Number (BIN). These identify the institution that issued the card to the card holder. The rest of the number is allocated by the issuer. The card number's length is its number of digits.

Cards participating in the BIN system include:

credit cards
debit cards
charge cards
stored-value cards
Electronic Benefit Transfer cards
In the United States, BINs are used in NCPDP pharmacy claims to identify processors, and are printed on all pharmacy insurance cards. BINs are the primary routing mechanism for realtime claims. Each processor has one or more BINs, which it divides into plans by using Group Number and Processor Control Number fields.

Online merchants may use BIN lookups to help validate transactions. For example, if the credit card's BIN indicates a bank in one country, while the customer's billing address is in another, the transaction may call for extra scrutiny.

The term "Issuer Identification Number" (IIN) is replacing "Bank Identification Number". See ISO 7812 for more information.

The prefixes and lengths for the most common card types are:

Card Type Prefix(es) Active Length Validation Symbol for coverage chart
American Express 34, 37[1] Yes 15[2] Luhn algorithm AmEx
Bankcard[3] 5610, 560221-560225 No 16 Luhn algorithm BC
China Union Pay 622 (622126-622925) Yes 16,17,18,19 unknown CUP
Diners Club Carte Blanche 300-305 Yes 14 Luhn algorithm DC-CB
Diners Club enRoute 2014, 2149 No 15 no validation DC-eR
Diners Club International[4] 36 Yes 14 Luhn algorithm DC-Int
Diners Club US & Canada[5] 55 Yes 16 Luhn algorithm DC-UC
Discover Card[6] 6011, 65 Yes 16 Luhn algorithm Disc
JCB[citation needed] 35 Yes 16 Luhn algorithm JCB
JCB[citation needed] 1800,2131 Yes 15 Luhn algorithm JCB
Laser (debit card)[citation needed] 6304, 6706, 6771, 6709 Yes 16-19 Luhn algorithm / unknown? Lasr
Maestro (debit card) 5020,5038,6304,6759 Yes 16,18 Luhn algorithm Maes
MasterCard 51-55 Yes 16 Luhn algorithm MC
Solo (debit card) 6334, 6767 Yes 16,18,19 Luhn algorithm Solo
Switch (debit card) 4903,4905,4911,4936,564182,633110,6333,6759 Yes 16,18,19 Luhn algorithm Swch
Visa 4[1] Yes 13,16[7] Luhn algorithm Visa
Visa Electron 417500,4917,4913,4508,4844 Yes 16 Luhn algorithm Visa

On November 8, 2004, MasterCard and Diner's Club formed an alliance. Cards issued in Canada and the USA start with 55 and are treated as MasterCards worldwide. International cards use the 36 prefix and are treated as MasterCards in Canada and the US, but are treated as Diner's Club cards elsewhere. Diner's Club International's website makes no reference to old 38 prefix numbers, and they can be presumed reissued under the 55 or 36 BIN prefix.

Effective October 1, 2006, Discover will now be using the entire 65 prefix, not just 650. Also, similar to the MasterCard/Diner's agreement, China Union Pay cards are now treated as Discover cards and accepted on the Discover network.

A search on VISA's website results in many references to card numbers being 16 digits long. However, searching for references to 13-digit cards will turn up no results. It might be presumed that 13-digit cards no longer exist and have been reissued as 16-digit cards, however old accounts may still use these numbers.

Switch will continue to exist until mid 2007, after that it will branded as Maestro. Maestro is now VISA Electron's main competitor in the European debit card market.

Solo can be used outside of Britain if the card displays Maestro.