UK and European Economic Area (EEA) retailers are facing a cost increase of around £150m a year to accept cross-border card payments.
UK businesses may be forced to take on an additional £36.5m, according to research by retail payments advisory firm CMSPI, alongside the British Retail Consortium (BRC).
The BRC has called on ministers and the Payment Systems Regulator (PSR) to take action against rocketing card fees.
After Brexit, transactions between the EEA and the UK are no longer capped at the intra-regional rate and instead classed as inter-regional transactions.
Card giants have been able to hike interchange fees on some online or “card not present” transactions by up to 475 per cent or increase their fees on all cross-border transactions.
New scheme fees are estimated to cost UK merchants £9.5m and EEA merchants £20.8m.
BRC payments policy adviser, Andrew Cregan, said: “Consumers and retailers on both sides of the Channel are on the hook for tens of millions in new card costs unless swift action is taken.
At a time when retailers are facing rising costs across the board, from higher energy prices to soaring shipping charges, it is likely that some of these five-fold fee increases will eventually be passed on to hard pressed consumers. British merchants alone will pay an extra £100,000 every single day just to process cross-border transactions, holding back British exports to Europe.”