F 42 — CARD ACCEPTOR IDENTIFICATION CODE:
This field carries the merchant number of the merchant that the terminal where the transaction took place is linked to. It is a 15-character alphanumeric value.
Transactions are settled into the merchant's account based on the merchant number carried in this field.
What does the merchant number identify?
The F42 field identifies the merchant that accepted the transaction. The merchant number is assigned by the acquirer at the time the contract is signed. The transaction amount, the commission, the payment due date, and which account it will be transferred to are all determined based on the definitions tied to this number.
How does it appear on the cardholder's side?
The merchant name and city information that the cardholder sees on their statement is not carried in the F42 field, but in the F43 (Card Acceptor Name/Location) field. However, for this information to match correctly, the merchant number in F42 must be defined correctly. If the cardholder sees a merchant name on their statement that they do not recognize, this can lead to unnecessary disputes.
Payment institutions and sub-merchants
For merchants operating through payment institutions or virtual POS providers, the F42 field generally carries the payment institution's merchant number. To identify the actual seller, sub-merchant information is sent in additional fields. Card schemes require this information to be sent correctly so that the cardholder can recognize the transaction.
Format of the value
F42 is a fixed-length, 15-character field. If the merchant number is shorter than 15 characters, the value is typically padded to 15 characters, either with trailing spaces or with leading zeros. Which padding method is used is specified in the relevant network's specification.
