A method and system for processing a financial transaction using an enhanced payment card through a multi-party payment card interchange network are provided. An authorization request message generated at a point of sale (POS) device associated with a merchant is received at a computer associated with the interchange network. The authorization request message includes a card identifier and relates to a transaction initiated by the cardholder with the merchant using the enhanced payment card. The transaction is electronically identified as involving the enhanced payment card by matching the received card identifier to a list of card identifiers stored within a database. A product code identifying the transaction as an enhanced payment card transaction is electronically added to the authorization request message. The merchant is instructed to transmit to the interchange computer an addendum file including enhanced transaction data for the enhanced payment card transaction.