A new application at the Competition Appeal Tribunal (CAT) seeks permission to bring an opt-out collective claim against Visa and Mastercard over the multilateral interchange fees (MIFs) UK businesses pay on card payments. Headlines put the potential value at around £5 billion. Nothing has been decided, and both schemes dispute the claim, but if you accept cards it is worth understanding what is being alleged and what you can usefully do now.

What has been filed

According to The Paypers, published on 27 October 2026, law firms have applied to the CAT for permission to pursue collective proceedings. The claim is funded by litigation funder Bench Walk Advisors and led by a former travel-sector executive who has pursued the schemes through earlier group actions. It alleges that UK businesses were overcharged on debit, credit and prepaid card payments from October 2020 onwards.

As reported, the proposed class covers UK businesses, organisations and charities with revenues below £100 million, estimated at around one million, who would be included automatically unless they opt out. Larger businesses would need to opt in. The tribunal has not yet decided whether the case can proceed. Mastercard has said it strongly disagrees with the basis of the claim, and Visa has said it regards interchange as a critical part of a secure digital payments ecosystem.

Why interchange sits at the centre

Interchange is the fee your customer's card-issuing bank receives each time a card is used, and it is usually the largest part of your card processing fees. Domestic UK consumer cards are already subject to regulatory caps, which we explained in our guide to card processing fees in the UK, so the case will turn on arguments about how the schemes set and apply these fees. Those arguments are for the tribunal, not for a blog post, and this article is general information rather than legal advice.

The practical point for a small business is simpler: most merchants cannot see how much of what they pay is interchange, how much is scheme fees and how much is their provider's margin. That makes it hard to judge any claim, or any quote, with confidence.

What UK SMEs should do this week

You do not need to act in haste, and you should be wary of unsolicited firms promising payouts. A sensible, low-cost approach looks like this:

  • Keep your records: retain merchant statements and processing reports back to October 2020 where you can, as volumes and fees will matter if you ever take part.
  • Follow official notices: opt-out and opt-in deadlines are set by the tribunal, so rely on its notices rather than marketing emails.
  • Take advice before deciding: whether to stay in, opt out or pursue a separate claim is a legal decision, so speak to a solicitor.
  • Do not budget for a payout: outcomes are uncertain and cases like this can take years, so keep compensation out of your forecasts.
  • Review what you pay today: whatever happens in court, fees are being charged now, and that is the part you can control.

How pricing transparency helps, and how Monek approaches it

With IC++ pricing, interchange, scheme fees and the provider's margin are shown separately, so you can see exactly where each pound goes. On a blended rate you pay one headline figure, which is simpler but hides the split. Both can suit different businesses, and the right choice depends on your card mix and volume.

Monek is an FCA-regulated payment provider (FRN 920628) with pricing from 0.99% blended, IC++ pricing for higher-volume merchants and next-day settlement. Our UK payment gateway includes a free WooCommerce plugin, Virtual Terminal, Pay by Link and native Xero integration, which makes your costs easier to see and reconcile. If you would like a clear view of what you pay on cards, talk to our team for a no-obligation rate comparison.