Debit and credit cards can cost different amounts to accept because your provider may price them separately. One underlying difference is interchange: where the UK's domestic consumer-card caps apply, the limits are 0.2% for debit and 0.3% for credit, but those caps do not limit your complete processing bill [1]. To compare quotes, use your actual debit and credit takings, payment counts and monthly charges.
If you run a café or restaurant, the useful question is how that difference affects a whole month. A low debit rate might look attractive, but it tells you little until you know what happens to the rest of your payments.
Are credit card payments always more expensive?
Check your tariff before assuming every credit payment costs more. At the time of writing (November 2026), Square lists one in-person processing rate of 1.75% for transactions with UK cards, rather than separate headline debit and credit rates [2].
Other offers separate the two categories. A tariff with separate rates needs a separate calculation for each: debit takings multiplied by the debit rate, then credit takings multiplied by the credit rate. Add the results before adding fixed fees.
That distinction matters when someone quotes an impressive starting rate. Ask which cards receive it and which cards are priced differently. A quote should let you reproduce the likely bill, rather than make you guess what “from” means.
What are interchange fees?
Interchange is generally paid by the business's acquiring bank to the customer's card-issuing bank and usually sits within the merchant service charge [1]. It is one cost inside card acceptance, rather than another name for your entire card-machine bill.
Cashflows explains its interchange-plus-plus pricing as interchange and scheme fees with a processing margin added; its breakdown distinguishes those three components [3]. If your quote uses that structure, ask the provider to show all three parts in its worked estimate.
The practical distinction is between an underlying cost and the price your business agrees to pay. Do not compare an interchange percentage with another provider's complete transaction rate. Put complete transaction charges alongside complete transaction charges.
What do the interchange caps actually cover?
The domestic caps concern consumer-card transactions where the merchant, acquirer and issuer are all in the UK [1]. They are not a promise that every debit or credit payment your business accepts falls within those limits.
The merchant service charge itself is not capped by these rules. [1] If your quoted debit rate is above 0.2%, that alone does not show that the interchange rule has been broken. Start by identifying which charge you are looking at.
For a usable quote, request separate treatment of UK consumer cards, commercial cards and overseas cards. Also separate counter payments from remote payments. Square's current pricing page, for example, distinguishes in-person, online and manually entered transactions and UK versus non-UK cards [2].
How much does the debit and credit mix matter?
Example: imagine a restaurant takes £20,000 a month across 500 card payments. For illustration only, a hypothetical tariff charges 0.4% on debit, 0.8% on credit and 3p per payment. These are invented example rates, not a TrustPOS offer or a market average. Assume every payment fits those two categories and exclude all monthly and additional charges.
| Monthly card mix | Debit percentage cost | Credit percentage cost | Payment fees | Total |
|---|---|---|---|---|
| £16,000 debit / £4,000 credit | £64 | £32 | £15 | £111 |
| £10,000 debit / £10,000 credit | £40 | £80 | £15 | £135 |
| £4,000 debit / £16,000 credit | £16 | £128 | £15 | £159 |
Example: continuing the hypothetical restaurant above, the takings and payment count stay the same. Only the card mix changes, yet the illustrated monthly cost moves by £48 between the first and last rows.
Use the share of money taken, rather than just the share of payment count, for the percentage calculation. If ten credit payments have much larger bills than ten debit payments, equal counts do not mean equal takings.
Why payment count still matters
A separate pence-per-payment charge needs its own calculation. It cannot be estimated from turnover alone.
Example: using the same hypothetical tariff, suppose £10,000 debit and £10,000 credit arrive across 2,000 payments instead of 500. The percentage cost remains £120. The 3p fees rise from £15 to £60, making the illustrated transaction total £180 instead of £135, before any other charges.
This is particularly useful when comparing a coffee counter with a sit-down restaurant. Build the quote around your own average bill and payment count; do not borrow another business's numbers because its monthly turnover looks similar.
How to compare two quotes fairly
Take one complete recent month and give both providers the same information:
- Debit takings and credit takings, with other categories listed separately.
- Payment counts, including any breakdown the tariff requires.
- How customers pay: at the counter, online or remotely.
- Recurring costs, including machine rental, till software and any other quoted charges.
- Contract length and exit costs, so a monthly reduction does not hide a switching expense.
Ask each provider to return a written monthly illustration and state its exclusions. Keep tax treatment consistent, and avoid adding a statement total again when its components are already included.
If you cannot find the card split, ask your provider for it. The PSR explains that the IFR includes requirements for acquirers to give merchants information on accepting different card brands and categories [1]. You can also use our guide to reading your card-machine statement to organise the figures.
Where TrustPOS options fit
The verified TrustPOS offers show why the whole calculation matters. myPOS Ultra is £20 a month plus VAT, with 0.32% plus 3p on debit transactions and 0.62% plus 3p on credit transactions; its card fees have a £20 monthly minimum, so if the calculated fees are lower, you pay the difference. Shift4 Solo has no monthly machine cost and charges 1.25% per transaction with no authorisation fee, whether the customer pays by debit or credit.
For a business needing a full till, Shift4 Dine is £39 per month plus VAT with standard transaction pricing of 0.9% plus 2p, on-site installation and the menu loaded. Its agreement is 12 months; early exit costs the monthly rental multiplied by the months remaining.
These are different setups. Compare the agreed card categories and all applicable charges, then check the equipment fits the job. Bring a recent statement and ask for one complete monthly comparison on the same figures. Any saving depends on your current charges, card mix and final terms.
Sources
- Payment Systems Regulator: the IFR and merchants, checked 18 October 2026.
- Square: UK processing fees and pricing, checked 5 November 2026. Competitor pricing described at the time of writing (November 2026).
- Cashflows: interchange explained, checked 18 October 2026.
This guide is general information, not financial advice. Any saving depends on your current charges, card mix and final terms.