Mastercard, Visa, and Revolut have faced a setback in their legal challenge against the UK's Payment Systems Regulator (PSR), which plans to impose caps on interchange fees for card transactions. The PSR highlighted that these companies significantly increased their cross-border interchange fees between 2021 and 2022, raising them from 0.2% to 1.15% for debit cards and from 0.3% to 1.5% for credit cards. This spike, attributed to post-Brexit changes, is estimated to cost UK businesses an additional £150-200 million annually. Legal expert Michelle Quinn points out that if the interchange fee cap is implemented, it could benefit retailers and consumers. Merchants may experience lower transaction costs, potentially leading to reduced prices for consumers. However, banks and fintechs could be adversely affected as interchange fees represent a significant revenue source for them. If capped too low, these companies might lose money on transactions, creating a dilemma that could reshape the financial landscape for card payments. The PSR's ongoing consultation on the methodology for the cap will guide its next actions in this contentious area.