Interchange Fee Regulation (IFR)
The 2015 EU regulation that capped the card networks' most important fee and rewrote a handful of their rules while it was at it.
Regulation (EU) 2015/751 is best known for the caps, in force since December 2015: 0.2 per cent of the amount for consumer debit cards and 0.3 per cent for credit cards. Before that, the interchange fee topped one per cent in several countries. Commercial cards are out of scope, as are three-party schemes like American Express, so long as they don't license card issuing to banks.
The surrounding rules matter just as much. Networks must separate the brand business from transaction processing, so a bank can have someone else do the processing. Co-badged cards are allowed and the merchant may pick which network runs the payment. Honour All Cards is narrowed, so accepting debit cards no longer means accepting expensive corporate cards. Cards issued outside the EEA fell outside the caps, and it took a separate commitment from Visa and Mastercard in 2019 to close that gap.