Interchange Fees Decoded: Why Your Card Machine Provider's Rate Is Not the Full Story

Interchange Fees Decoded: Why Your Card Machine Provider's Rate Is Not the Full Story

You signed up for a card machine. You were told the rate. You thought you understood what you were paying.

Then the invoice arrived.

If that sentence landed with recognition, you are not alone. Thousands of UK business owners every year discover that the rate they agreed to and the money leaving their account are two different conversations. Not because anyone necessarily lied to them. But because card processing is built on layers, and most providers only ever talk about the top one.

This piece pulls back every layer. By the end, you will know exactly what interchange fees are, who collects them, why they differ so dramatically between cards, and what you can actually do about it.

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Start Here: What You Think You Pay vs. What You Actually Pay

When a card machine provider quotes you a rate, say 1.5% per transaction, that number is called the Merchant Service Charge (MSC). It sounds like one thing. It is actually three things bundled together:

1. The interchange fee — paid to the bank that issued the card your customer used
2. The scheme fee — paid to the card network (Visa or Mastercard)
3. The acquirer's margin — the portion your card machine provider actually keeps

Think of it like a pint of milk on a supermarket shelf. The price you see covers the farmer, the dairy, the logistics company, and the supermarket's profit. You pay one number at the till, but it flows to multiple parties. Card processing works the same way.

The critical difference is this: with the milk, everyone in the supply chain agreed to their cut before it hit the shelf. With card processing, the interchange fee is set by Visa and Mastercard, not by your provider. Your provider has limited control over it. And yet most pricing conversations never mention it.

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So What Exactly Is an Interchange Fee?

An interchange fee is a charge paid by the merchant's bank (the acquirer) to the customer's bank (the card issuer) every time a card transaction is processed.

In plain terms: your customer's bank gets paid a small percentage every time their cardholder spends with you.

Why? The logic, as established by Visa and Mastercard when interchange was first introduced in the 1970s, is that the issuing bank takes on risk. It guarantees the payment, manages fraud, funds any rewards programme attached to the card, and handles chargebacks. Interchange is supposed to compensate for that.

Whether you find that logic convincing is a separate matter. What matters for your business is that it is real, it is baked into every card transaction, and it varies enormously depending on the type of card your customer uses.

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Why the Rate Changes Card by Card

This is where most business owners have a lightbulb moment. Not all cards cost the same to accept. The interchange fee on a basic debit card is very different from the interchange fee on a premium travel rewards credit card. And that difference comes out of your pocket.

Here is a rough illustration using figures consistent with post-Brexit UK interchange caps as regulated under the Interchange Fee Regulation (IFR):

Since Brexit, the UK retained the EU interchange caps for consumer cards under domestic rules enforced by the Payment Systems Regulator (PSR). But commercial cards and cards issued outside the UK are not subject to those caps. When an American tourist pays you with their airline rewards Visa, the interchange on that transaction bears no resemblance to the interchange on a British debit card.

If your provider quotes you a blended rate, that 1.5% figure may actually be profitable for them on UK debit transactions and barely breakeven or loss-making on uncapped cards. How that is managed, and who absorbs the difference, varies by provider and contract structure.

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Blended Pricing vs. Interchange-Plus: The Choice That Actually Matters

This distinction is arguably the most important thing you will read in this article.

Blended pricing means your provider charges you one flat rate regardless of what card the customer uses. Simple to understand. Potentially expensive.

Interchange-plus pricing (sometimes called cost-plus) means your provider passes through the actual interchange and scheme fees, then adds their margin on top transparently. You see every component separately.

For a business that takes mostly UK consumer debit cards, a blended rate can actually work out fine. The debit interchange is capped at 0.2%, so even a blended rate of 1.5% gives the provider enough margin to run their service and the business gets predictability.

But for any business with a high proportion of corporate cards, foreign cards, or premium credit cards — photographers invoicing large commissions, legal firms, high-end retailers, travel companies — blended pricing can become genuinely costly. You are effectively subsidising the provider on every premium card that comes through your terminal, because you agreed to a flat rate before knowing what card your customer would use.

Interchange-plus pricing solves the transparency problem. You pay what the network charges, plus a clear fixed margin for your provider. The downside is variability. Your monthly bill becomes harder to predict. The upside is that you stop overpaying on low-cost cards and you can see exactly what you are being charged and why.

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A Real-World Example

Let us say you run a camera shop in Manchester. A customer buys a full-frame mirrorless kit for £3,200. They pay on their business credit card.

Under a blended rate of 1.5%, you pay £48 in processing fees.

Now consider: the interchange on a UK commercial credit card can reach 1.6% to 1.8% on its own, before scheme fees and your provider's margin. Your provider may actually be losing money on this transaction, or passing the real cost back to you through opaque surcharges in the small print.

Under an interchange-plus model, you would see the actual interchange (say 1.7%), the scheme fee (perhaps 0.1%), and the acquirer margin (say 0.3%). Total: approximately 2.1%, or £67.20. That is more than the blended rate on that single transaction. But it is honest. And for the hundreds of transactions where the customer uses a capped debit card, you would be paying the real cost, which would be significantly lower than your blended rate.

Over a year, for a business with mixed card types, interchange-plus almost always works out cheaper for merchants with higher volumes and a more varied customer card mix.

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What the PSR Has Been Doing About This

The Payment Systems Regulator has not been passive on this issue. In its 2023 review of card scheme and processing fees, the PSR found that Visa and Mastercard had increased their scheme and processing fees significantly in the years following Brexit, with combined increases of around 25% to 30% between 2017 and 2021 for some merchant categories.

The PSR's market review published in 2024 concluded that competition in the acquiring market is not working as well as it should for smaller merchants, who lack the bargaining power to negotiate rates and rarely have the information needed to compare providers meaningfully.

That is an official UK regulator saying, in considered language, what many small business owners already know instinctively: this market is not set up to make things easy for you.

The regulator has proposed greater fee transparency and is consulting on whether further intervention is needed. Progress is slow. In the meantime, your best defence is your own understanding.

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Scheme Fees: The Often-Forgotten Third Layer

Interchange gets the attention. Scheme fees rarely do. But they are growing.

Visa and Mastercard charge their own fees to both issuers and acquirers for using their networks. These include authorisation fees, network access fees, cross-border fees, and a variety of other levies that can vary by transaction type, geography, and card category.

For most small merchants on a blended contract, these fees are invisible. They are absorbed into the blended rate. But they are real, they are increasing, and they are one reason why provider margins are under pressure and why some providers have raised their blended rates in recent years without a clear explanation.

If you ever request an interchange-plus breakdown from a provider, insist that scheme fees are also itemised separately. Some providers bundle interchange and scheme fees together under the label "wholesale cost" to avoid showing you each component.

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What This Means for Your Business: Practical Takeaways

1. Ask your provider for a full cost breakdown. Request a written explanation of how your rate is structured: interchange, scheme fees, and acquirer margin. If they cannot or will not provide this, that tells you something.

2. Know your card mix. Ask your provider for a statement showing the breakdown of transactions by card type. How many are consumer debit? How many are business credit? How many are from non-UK issued cards? This tells you whether a blended rate is working for or against you.

3. Consider interchange-plus if your average transaction value is high. The higher the ticket size, the more each basis point costs you in absolute terms. A £50 sale at 1.5% costs 75p. A £5,000 sale at 1.5% costs £75. At that scale, understanding what you are actually paying matters enormously.

4. Do not assume a lower headline rate is always cheaper. A provider quoting 1.2% with hidden commercial card surcharges may cost you more than a provider quoting 1.6% with genuine interchange-plus transparency.

5. Watch the PSR's ongoing reviews. Regulation in this space is moving. The PSR's work on scheme fees and acquirer market competition could materially change pricing dynamics for UK merchants within the next two to three years.

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The Short Version

Your card machine provider's headline rate is a starting point, not the full answer. Interchange fees go to your customer's bank, not to your provider. Scheme fees go to Visa or Mastercard. Your provider keeps what remains. Each layer varies by card type, geography, and the structure of your contract.

Understanding this does not require a finance degree. It requires someone to explain it plainly. Consider this that explanation.

Now go and look at your last processing statement with fresh eyes. The numbers will start to make a different kind of sense.

Sources

1. Payment Systems Regulator (PSR) — Card-acquiring market review, Final Report 2021 and subsequent market review updates 2023/2024: https://www.psr.org.uk/our-work/card-acquiring-market-review/
2. Payment Systems Regulator (PSR) — Review of Visa and Mastercard scheme and processing fees, Interim Report 2023: https://www.psr.org.uk/our-work/scheme-and-processing-fees/
3. UK Interchange Fee Regulation (retained EU law, as it applies post-Brexit) — referenced via FCA and PSR guidance on consumer card interchange caps (0.2% debit, 0.3% credit): https://www.fca.org.uk/firms/interchange-fees
4. European Commission — Background on Interchange Fee Regulation (EU) 2015/751, foundational framework from which UK rules derive: https://ec.europa.eu/competition/sectors/financial_services/interchange_fees_en.html
5. Mastercard UK interchange rate schedule (publicly available for reference): https://www.mastercard.co.uk/en-gb/business/overview/merchant-interchange-rates.html
6. Visa Europe interchange reimbursement fees schedule (publicly available): https://www.visa.co.uk/about-visa/visa-in-europe/fees-and-interchange.html
7. BIS CPMI — Retail payments: mapping out the fast lane (2022), for context on global payment fee structures and acquirer/issuer dynamics: https://www.bis.org/cpmi/publ/d200.htm
8. McKinsey Global Payments Report 2023 — Data on scheme fee growth and merchant cost trends: https://www.mckinsey.com/industries/financial-services/our-insights/the-2023-mckinsey-global-payments-report
9. UK Finance — UK Payment Markets Summary 2023, for context on card transaction volumes and merchant acceptance trends in the UK: https://www.ukfinance.org.uk/system/files/2023-06/UK-Payment-Markets-Report-2023-FINAL.pdf
10. The Paypers — Coverage of PSR scheme fee review and UK merchant acquiring market: https://thepaypers.com

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Disclaimer

The views and information shared in this post are for educational and informational purposes only and do not constitute financial, legal, or professional advice. While every effort is made to ensure accuracy, Klipy UK Limited accepts no liability for decisions made based on this content. Payment processing rates, regulations, and product features referenced are subject to change. Klipy UK is an authorised seller of Teya payment solutions. Where third-party sources are cited, links are provided for reference; Klipy UK does not endorse or guarantee the accuracy of external content. For personalised guidance on your business payment needs, please contact us directly at editor@klipy.uk.