what is an issuer identification number iin 
the issuer identification number iin on a payment card indicates which bank or other financial institution issued that card and is responsible for it these numbers are found on credit debit and other types of payment cards worldwide issuer identification numbers are sometimes referred to as bank identification numbers bins understanding issuer identification numberscredit card numbers vary in length frequently 15 or 16 digits but sometimes as many as 19 the first six or eight of those digits represent the issuer identification number the very first digit is known as the major industry identifier mii number these numbers were established by the international organization for standardization iso and the international electrotechnical commission in a standard known as iso iec 7812 1the mii indicates which industry the number is associated with for example numbers 3 4 5 and 6 apply to the banking and financial sectors while 1 and 2 apply to the airline industry 7 to the oil industry and so forth for that reason credit and debit cards will begin with either a 3 4 5 or 6 depending on which card processing network such as visa or mastercard they are tied into 2specifically to use some well known cards and card networks as examples visa cards begin with a 4 mastercards with a 2 or a 5 discover cards with a 6 and american express cards with a 3 2the remaining five or seven digits in the iin indicate the bank or other financial institution that issued the card in recent years newly issued iins have consisted of eight digits while earlier ones had six digits this change was made to accommodate the rapidly growing numbers of cards and cardholders 3 for example visa cards issued by chase will have different iins from visas issued by capitol one or wells fargo although they will all begin with a 4 following the iin on the card will be a series of numbers unique to that specific cardholder the very last number known as the check digit or check sum is used to validate the card number and make sure you ve typed it in correctly if you re buying something online through a computation called the luhn algorithm the entire string of numbers which identify the card network the financial institution that issued the card and the individual the card belongs to is often referred to as the primary account number or pan that s how many different number combinations a typical 15 or 16 digit credit card number allows for according to american express a quadrillion is equal to 1 000 trillion or 1 000 000 000 000 000 3the importance of issuer identification numbersissuer identification numbers and the individual account numbers that accompany them allow merchants and others to verify that a card is valid and that the user s account has sufficient funds available to cover the transaction and they make it happen almost instantaneously credit card numbers vs account numbersthe number that s printed on your credit card and your account number with the financial institution that issued it can be two different things as the credit bureau experian points out if your card is lost or stolen then you ll receive a replacement card with new credit card numbers but your account number will remain the same if you don t already know it you should be able to find your account number by consulting your monthly credit card statement 4