The headline rate on a card acquiring quote tells you almost nothing. Two providers can quote you 1.5% and charge you entirely different amounts by the end of the year, because the 1.5% is built differently in each case. One has tucked a £25/month minimum charge and a 4p authorisation fee behind the rate card. The other is applying the same 1.5% to your debit card payments even though those transactions actually cost the acquirer 0.20% in interchange. The rest is their margin, and you are not meant to see it.
This guide explains how the three main UK card processing pricing models actually work, what each one costs on a real £20,000/month volume, and which model suits which type of UK business. Flat-rate wins on simplicity and the freedom to walk away. Interchange-plus wins on cost transparency and, above roughly £8,000–£15,000/month, on total spend for a business with a predominantly UK consumer debit card base. Blended sits in the middle and offers predictability without the full transparency your acquirer would probably prefer you not to have.
Interchange vs Blended vs Flat-Rate at a Glance
| Feature | Flat-Rate | Blended | Interchange-Plus (IC+) |
|---|---|---|---|
| How the rate is set | Single % for all cards of one type (e.g. all standard UK domestic cards) | Different rates by card group (debit / credit / commercial), but each rate bundles interchange, scheme fees, and acquirer margin | Interchange passed at actual cost + acquirer margin stated separately |
| Can you see acquirer margin? | No | No | Yes |
| Who it suits | Lower volumes; no-contract flexibility; businesses needing wide payment method range | Mid-market businesses wanting predictability; blended rate absorbs card-mix variation | Businesses above ~£8,000–15,000/month; predominantly UK consumer debit card base |
| Contract | None (Stripe, Square, SumUp) | Typically 12–36 months with exit fees | Typically 12–36 months with exit fees |
| PSR transparency finding | Zero interchange visibility | Most UK SMEs on blended cannot isolate interchange cost or meaningfully compare acquirers (PSR MR18/1.8) | Full cost visibility; enables acquirer benchmarking |
| UK providers (2026) | Stripe, Square, SumUp | Teya, Tyl by NatWest, Dojo Fix, Worldpay standard, Elavon standard plans | Dojo Flex (£100k+/yr), Worldpay enterprise, Elavon bespoke, Adyen (IC++) |
The Payment Systems Regulator’s card-acquiring market review (MR18/1.8, final report 2021) reached an awkward conclusion for the industry: the bundled nature of blended pricing made it genuinely difficult for merchants to compare acquirers or confirm whether interchange savings from the 2015 IFR caps had been passed on. The PSR’s scheme and processing fees market review is now implementing remedies meant to force greater price transparency. Until those land, most UK SMEs on blended pricing are still trading without knowing what their interchange cost actually is. That is not an accident of the market; it is the structure of the product.
What Is Interchange-Plus (IC+) Pricing?
Every card payment in the UK involves three separate costs: interchange (paid to the card issuer, whether that is Barclays, HSBC, or whoever your customer banks with); scheme fees (paid to Visa or Mastercard for operating the network); and the acquirer’s own margin (the profit Worldpay, Dojo, or Elavon keeps for providing you the merchant account and processing service).
Under IC+ pricing, interchange is passed to you at cost, at the actual rate for each card type. Your acquirer adds a stated mark-up on top. That mark-up is the negotiable part, and because it is visible, you can actually benchmark it against competitors instead of guessing. Typical UK acquirer margins under IC+ run at 20–50 basis points (0.20%–0.50%) plus a per-transaction fixed fee. For IC+ contracts, scheme fees are usually bundled into the acquirer mark-up rather than shown as a separate line.
Interchange-plus-plus (IC++) goes one step further: it separates all three cost lines. Adyen uses IC++. Their pricing shows interchange at cost, scheme fees at cost, and then adds 0.60% plus £0.13 per transaction as the Adyen processing component. For high-volume businesses, IC++ gives you the clearest view of exactly what each component costs and the most leverage the day you sit down to renegotiate.
The IFR caps that set UK domestic consumer interchange at 0.20% (debit) and 0.30% (credit) make IC+ pricing particularly attractive for businesses with a predominantly UK consumer card base. The caps do not apply to commercial and corporate cards. A business card issued to a UK limited company carries interchange of approximately 1.30%–1.80%, uncapped, which is six to nine times the consumer debit rate. On an IC+ contract, you pay that higher interchange in full on every corporate card transaction. If your clients are businesses rather than consumers, that one line item changes the entire calculation.
What Is Blended Pricing?
Blended pricing bundles interchange, scheme fees, and acquirer margin into one or two headline rates organised by card group. You might see “personal debit: 0.85%” and “personal credit: 1.20%” and “commercial/international: 1.60%” on a quote, and each of those rates is a composite. They include a layer of acquirer margin you cannot isolate from the interchange component, however hard you stare at the statement.
The structural consequence is worth understanding. Under the UK IFR, consumer debit interchange is capped at 0.20%. A blended rate of 0.85% for personal debit means the acquirer is applying 0.65% on top of the actual interchange cost. Some of that is scheme fees (typically 0.02%–0.15%), and the rest is pure acquirer margin. You have no way to tell how much without a separate IC+ quote to compare against, which is precisely the position the structure encourages.
For a business with a mixed card base, blended pricing offers predictability. The acquirer absorbs the variance: if your customers start using more premium rewards cards this month, your rate does not move. The acquirer takes the hit. The inverse is also true, and it is the part that costs you money. If your customers are overwhelmingly using basic UK debit cards, where the acquirer’s interchange cost is 0.20%, the acquirer keeps the difference between that cost and your blended rate. Debit-heavy businesses on blended pricing are quietly subsidising the processing cost of every premium card in the acquirer’s merchant portfolio.
Blended pricing is not a trick. It is a legitimate commercial model that trades transparency for predictability. The problem is that many businesses are sitting on blended contracts without ever being told the trade-off was made on their behalf. That is the condition the PSR identified in 2021 as preventing meaningful competition in UK card acquiring.
What Is Flat-Rate Pricing?
Flat-rate pricing applies a single percentage to all transactions of a given category. Stripe charges 1.5% + 20p for standard UK domestic cards and 1.9% + 20p for premium UK domestic cards. One rate regardless of whether the customer pays with a basic current account debit card or a cashback-earning travel credit card. Square charges 1.75% in-person on all UK cards. SumUp charges 1.69%.
Flat-rate is blended pricing taken to its logical extreme. The acquirer absorbs all card-mix variation internally and offers you a single, predictable number. That simplicity costs money at scale, because the flat rate has to be set high enough to leave the provider a margin across their entire merchant portfolio, including all the commercial, premium, and European cards that carry high interchange. If your customers are predominantly using basic UK consumer debit cards, you are the one paying the most for the simplification.
What flat-rate providers give you in return is real: no monthly fees, no contracts, no minimum charges, instant setup, and, in Stripe’s case, an international payment method ecosystem that traditional acquirers cannot match without serious additional integration work. For a Shopify merchant adding Klarna, iDEAL, and SEPA Direct Debit alongside standard card payments, Stripe’s ecosystem value can be worth the per-transaction premium well beyond the volume crossover point on raw card rates alone. That is not a failure of the calculation; it is a piece of the calculation rate comparisons routinely miss.
UK Interchange Fees in 2026: Why They Matter
Interchange is not a line item on your Stripe dashboard. It is the cost foundation every pricing model is built on top of. Once you can see it, you read every acquiring quote you receive differently.
The UK Interchange Fee Regulation (UK IFR), retained from EU law and administered by the PSR, caps domestic consumer card interchange at 0.20% for debit and 0.30% for credit. These caps have been in place since December 2015 and are confirmed as current UK law under the Interchange Fee (Amendment) (EU Exit) Regulations 2019.
Four categories are not covered by those caps:
- UK commercial and corporate cards: Approximately 1.30%–1.80% depending on card type and scheme, uncapped under IFR. On an IC+ contract, every corporate card payment from a business client costs you six to nine times more in interchange than a consumer debit transaction. The 10% commercial card slice in the worked example below pulls disproportionate weight on the total cost.
- EEA-issued consumer cards (post-Brexit cross-border): Approximately 1.00% for consumer debit and ~1.15% for consumer credit, against 0.20%/0.30% domestic. The PSR’s MR22/2.6 cross-border interchange review is ongoing but no cap has yet been applied. UK businesses serving European tourists, online customers, or B2B buyers using EEA-issued cards wear that gap directly under IC+ pricing.
- Non-EEA international cards: Higher still, with no UK or EEA regulatory ceiling.
- American Express: Amex operates a closed-loop network and sets its own interchange outside the IFR framework. Generally the highest-cost scheme for UK SMEs accepting Amex.
A business that describes itself as “mostly UK consumer cards” needs to be specific about what “mostly” actually means. At 70% UK consumer debit, 20% UK consumer credit, and 10% commercial/other, the blended effective interchange cost is approximately 0.37%, almost double a pure-debit figure of 0.20%. The worked example below makes that concrete.
The PSR’s scheme and processing fees review (CP25/3, December 2025) is targeting a separate but related problem: Visa and Mastercard’s scheme fees have risen significantly since 2014 without adequate competitive pressure. The ITC and Pricing Governance remedies expected to finalise in 2026 will require schemes to provide acquirers with clearer, actionable pricing information. The PSR itself noted in MR18/1.8 that previous interchange savings from the 2015 IFR caps were not reliably passed on to merchants. There is no certainty the 2026 remedies will end any differently, and you should not price your switching decision as if they will.
Worked Example: Card Costs Under Each Model
Assumptions: £20,000/month in UK card turnover. Average transaction value: £45 (approximately 444 transactions/month). Card mix: 70% UK consumer debit (IFR-capped interchange: 0.20%), 20% UK consumer credit (IFR-capped interchange: 0.30%), 10% commercial cards (interchange approximately 1.60%, uncapped). All in-person or domestic online. No EEA or international cards in this illustration.
Blended effective interchange on this card mix: (70% × 0.20%) + (20% × 0.30%) + (10% × 1.60%) = 0.14% + 0.06% + 0.16% = 0.37%.
| Pricing model | Rate applied | % cost on £20k volume | Fixed fees (444 transactions) | Estimated monthly total |
|---|---|---|---|---|
| IC+ — illustrative competitive rate | Interchange at cost (0.37% blended on this card mix) + 0.35% acquirer margin + 5p per transaction | 0.72% | 444 × £0.05 = £22 | ~£166 |
| Blended — Tyl by NatWest published rate | Personal cards: 1.39% + 5p; commercial cards (10%): 1.99% + 5p | ~1.45% weighted | 444 × £0.05 = £22 | ~£312 |
| Flat-rate — Stripe standard UK cards | 1.5% + 20p per transaction | 1.50% | 444 × £0.20 = £89 | ~£389 |
IC+ figure uses an illustrative acquirer margin of 35 basis points + 5p fixed, which is competitive but not exceptional mid-market IC+ pricing. Your actual rate will depend on your card mix, volume, and negotiation. Blended Tyl figure uses published tariff (1.39% + 5p personal; 1.99% + 5p other), weighted for the stated card mix. Stripe applies 1.9% + 20p to premium UK cards; this illustration assumes all domestic cards qualify at 1.5%; commercial cards under Stripe’s classification may attract the higher rate.
The indicative IC+ saving on this card mix works out at roughly £146/month versus blended, or £223/month versus flat-rate, which is £1,750–£2,700/year. Set that saving against contract exit costs, MMSC risk in quiet months, and the switching friction of underwriting and integration before you treat it as money in your pocket.
Change the card mix and the calculation shifts noticeably. At 90% consumer debit, 10% consumer credit, no commercial cards, the blended interchange drops to ~0.21% and the IC+ saving over flat-rate expands to roughly £240/month. Add 30% commercial cards and the blended interchange rises to ~0.62%, which collapses the IC+ saving over flat-rate to under £100/month. Card mix is the most important input in this calculation, and it is the one most business owners have never been shown.
Which Hidden Costs to Watch For
The three pricing models differ not just in their headline rates but in which ancillary costs are standard in each. Flat-rate PSPs are generally clean: transaction rate, no monthly fee on standard plans, no minimum, no separate authorisation fee. Traditional acquirer contracts, where IC+ and blended tend to live, carry a longer list of potential additions, and any of them can quietly outweigh the rate advantage you switched for.
Authorisation fee
Up to 4p per transaction, charged on every authorisation request whether the transaction is approved or declined. If you run a subscription business, a ticketing operation, or any service where customers have stored card details that may have expired, you are paying authorisation fees on transactions that never complete. At 444 monthly authorisations with a 10% decline rate and a 4p fee, that adds £1.78/month at this scale, trivial in this example, but real at higher volumes and in business categories where decline rates run hotter.
Monthly minimum service charge
Most traditional acquirer contracts include a monthly minimum service charge (MMSC) of £10–£30. If your card processing fees for the month do not reach the floor, you pay the shortfall. For a café that closes for a fortnight in January, a seasonal retailer quiet from March to August, or any business that pauses operations for weeks at a time, the MMSC is a dead cost that recurs every quiet month. It does not appear anywhere near the headline rate in the sales conversation. It is the line item that makes the total cost calculation look very different in the months you needed the contract to flex.
PCI compliance fee
£5–£15/month on traditional acquirer contracts. Some providers bundle this into the transaction rate; others charge it separately and do not make it prominent at the quote stage. A non-compliance fee applies if you miss the annual SAQ deadline, typically higher than the standard monthly charge. Flat-rate PSPs handle PCI compliance at their layer for hosted integrations and do not add this as a separate line.
Chargeback fee
£15–£25 per dispute, charged regardless of outcome in most contracts. For businesses with low dispute rates this is background noise. For subscriptions, travel, event bookings, or any category with elevated dispute risk, it is a real operating cost and needs to be in your total cost of ownership calculation before you choose a contract.
Settlement timing — the cash-flow cost
Not a fee, but a real cost that does not appear in any rate comparison. Stripe UK’s standard settlement is T+3 business days. Dojo and Worldpay are typically T+1. Tyl by NatWest settles same-day to a linked NatWest account. For a business processing £20,000/month with tight working capital, the difference between T+1 and T+3 leaves an additional £1,300–£2,000 sitting in transit at any given moment, roughly three days of revenue at constant volume. That is not abstract. It is the cash you cannot use to pay a supplier on the 28th or your team on the 30th.
Contract exit fees and terminal rental
Worldpay contracts have been documented at 12–36 months with early termination fees of several months’ contracted charges. Terminal leases from traditional acquirers can run separately from the acquiring contract, which means switching acquirers does not necessarily end your terminal rental obligation. Dojo and Tyl operate month-to-month terminal rental, which is a structural improvement worth naming. But it also means the terminal rental cost is a permanent line item, not a sunk cost that disappears after a lease period.
Gateway fee
Some acquirers charge a per-transaction gateway fee on top of the processing rate. Elavon‘s Core All-in-one plan adds 16p per transaction as a separate gateway component. At 444 transactions/month that adds £71/month, enough on its own to reverse the cost advantage of a 0.99% processing rate over a 1.5% flat-rate alternative on a £20k/month volume. The rate card looked cheaper. The invoice was not.
When Does Each Pricing Model Make Sense for a UK Business?
Below £8,000–10,000/month: flat-rate or blended
Below this volume, go with a flat-rate PSP or a well-priced blended contract. The per-transaction saving from IC+ is real, but in absolute monthly pounds it is unlikely to justify the underwriting process, the contract commitment, and the MMSC floor risk. Stripe, Square, or SumUp give you functional acquiring with no monthly overhead, no exit risk, and instant access to alternative payment methods that traditional acquirers cannot easily match. Operational simplicity is a real cost saving, and one founders often underestimate until they have spent a fortnight chasing a separate gateway vendor over a settlement file format.
£10,000–50,000/month with a predominantly UK consumer debit base: IC+ is worth calculating
Request an IC+ quote from Dojo Flex (accessible from £100k/year), Elavon bespoke, or Worldpay at this volume tier. The worked example above suggests savings of £140–£220/month at £20k, real money, though not enough to absorb a steep exit fee from a long contract at the lower end of this range. Pull your card mix breakdown from your current PSP first; it is the single most important input. Run the full cost comparison including MMSC, authorisation fees, and gateway fees, not just the headline rate. The headline figures will mislead you otherwise.
Above £50,000/month: IC+ or IC++
At this volume level, IC+ is the default recommendation for a business with a majority UK consumer card base. The saving over flat-rate at £50k/month on the card mix in the worked example sits in the region of £550–£950/month. Adyen’s IC++ model becomes financially viable here if your transaction fees clear their minimum monthly invoice. At this scale the acquirer margin itself becomes the primary negotiating variable: 10 basis points represents £500/month, which is a salary line, not a rounding error.
High commercial or international card proportion: recalculate before switching
A business whose customers or clients predominantly pay with corporate purchase cards, EEA-issued cards, or non-EEA cards faces uncapped interchange rates of 1.00%–1.80% under IC+. A blended commercial card rate of, say, 1.60% may be more predictable, and in some cases cheaper, than IC++ at the actual commercial interchange your customers carry. This is the scenario where blended pricing’s absorption of card-mix variance is an operational benefit, not just a transparency trade-off. Do not switch to IC+ without running the numbers on your actual commercial card proportion; the consumer-debit story does not apply to you.
Seasonal or unpredictable volume: flat-rate
The no-contract model at Stripe and Square means your monthly costs scale to zero in months with no card transactions. An MMSC of £15–£25/month at a traditional acquirer is manageable in peak season and a dead cost in a quiet month of a 24-month contract. Market traders, festival vendors, seasonal hospitality, businesses that pause for extended periods: the contract-free model has a financial value the per-transaction rate comparison simply does not capture.
When blended is the right answer even at higher volumes
Blended works for a business with genuinely unpredictable card mixes: a venue that serves local debit card regulars on weekdays and international credit card visitors on weekends, with no reliable forecast of the proportion. The blended rate absorbs the variance without requiring you to monitor card-mix shift month to month. It also suits businesses that want a dedicated merchant account, and the contractual recourse that brings, without the volume to justify an IC+ negotiation and without the operational appetite to read an itemised IC+ statement every month.
Which UK Providers Offer Each Model in 2026
| Provider | Pricing model | Published rate (UK domestic) | Monthly fee | Contract | Settlement (UK) |
|---|---|---|---|---|---|
| Stripe | Flat-rate | 1.5% + 20p (standard UK cards); 1.9% + 20p (premium UK cards); 2.5% + 20p (EEA) | None | None | T+3 business days |
| Square | Flat-rate | 1.75% in-person; 1.4% + 25p online (UK cards); +1.5% for international cards (from April 2026) | None | None | T+1 |
| SumUp | Flat-rate | 1.69% (PAYG); 0.99% on Payments Plus plan (£19/month) | None (PAYG) / £19/month (Plus) | None | T+1 (to SumUp account) |
| Teya | Blended | 1.29%–1.90% (quote-dependent on card mix and turnover) | Terminal rental £24.90/month | Contract (terms vary) | T+1 |
| Tyl by NatWest | Blended | 1.39% + 5p (personal UK and EEA cards); 1.99% + 5p (all other cards) | Terminal rental (amount varies) | Contract | Same-day (to linked NatWest account) |
| Dojo Fix | Blended | Quote required (contact Dojo for current Fix rates) | Monthly fee (amount varies) | Contract | T+1 |
| Dojo Flex | IC+ | IC+ (interchange at cost + acquirer margin); available from £100k/year (~£8,300+/month) | Monthly fee (amount varies) | Contract | T+1 |
| Elavon | Blended (standard plans); IC+ (bespoke) | 0.99%–1.75% on published plans (personal debit and credit only; commercial card rates differ and are not published); IC+ by bespoke quote | £15–£18/month terminal; ~£4.50/month PCI compliance | Contract | 48h standard; next-day available on certain plans |
| Worldpay | Blended (standard); IC+/IC++ (enterprise) | Not published — bespoke quote required above £75k/year threshold; IC+ available at higher enterprise volumes | £15/month MMSC (above £75k/year) | 12–36 months; ETF applies | Typically T+1 |
| Adyen | IC++ (interchange-plus-plus) | Interchange at cost + scheme fees at cost + 0.60% + £0.13/transaction | Minimum monthly invoice (amount not publicly disclosed; contact Adyen sales) | Contract | T+1 (bank-dependent) |
Rates sourced from provider websites and third-party reviews, May 2026. Bespoke rates are negotiable and will differ from published figures at sufficient volume.
Final Verdict: Which Pricing Model Should You Choose?
There is no single winner here, and any guide that names one is selling you something. The model that costs your business least is decided by two numbers you control and one you have to find out: your monthly card volume, your appetite for a contract, and your card mix. Get the card mix breakdown from your current provider before you do anything else, because it moves the answer more than the headline rate ever will.
If you turn over under roughly £8,000–10,000/month, or your trade is seasonal, start with flat-rate. SumUp and Square charge nothing in a zero-transaction month, tie you to no contract, and cost you nothing to leave. The per-transaction premium you pay is the price of never having to think about an MMSC floor or an exit fee, and at that volume it is the right trade. Stripe earns its place where you need its alternative payment methods and developer ecosystem more than you need the lowest card rate.
Between £10,000 and £50,000/month with a predominantly UK consumer debit base, interchange-plus is worth calculating. Request a quote from Dojo Flex, Elavon, or Worldpay, run the full cost including MMSC and gateway fees, and treat the first margin you are offered as an opening position, not a price. Above £50,000/month, IC+ is the default, and Adyen‘s IC++ becomes viable for the businesses that want every cost line itemised. Where your customers pay mostly on commercial, corporate, or international cards, run the numbers before switching: blended’s absorption of that uncapped interchange can genuinely win.
The bottom line. Flat-rate for low or seasonal volume and operational simplicity; interchange-plus once you are consistently above £8,000–10,000/month on a debit-heavy mix; blended where your card mix is genuinely unpredictable or commercial-heavy. The decisive variable is your card mix, not the rate on the front of the quote — so get that breakdown first, then compare on total annual cost, never the headline percentage.
Frequently Asked Questions
No. IC+ passes interchange at actual cost, which is highly competitive for UK consumer debit cards capped at 0.20% under the IFR. But if your customers frequently pay with corporate cards, premium rewards cards, or EEA-issued cards, the uncapped interchange rates on those transactions, estimated at 1.00%–1.80%, mean your effective IC+ rate can exceed a flat-rate alternative. A business with 30% commercial card volume on IC+ may pay more than the same business on a well-negotiated blended rate. Run the calculation on your actual card mix, not the consumer debit headline figure, before you go anywhere near an IC+ quote.
For a UK SME with a majority consumer debit card base, IC+ starts producing meaningful savings somewhere between £8,000 and £15,000/month in card turnover. Dojo’s Flex Plan becomes available at £100k/year (~£8,300/month), which is the most accessible IC+ entry point for growing businesses. Below that range, the saving in absolute pounds is unlikely to justify the contract commitment. Above £50,000/month with predominantly UK consumer cards, IC+ is the natural choice. The crossover point moves lower if your debit card proportion is very high, and higher, or disappears entirely, if you process significant commercial or international card volume.
No. Stripe, Square, and SumUp do not show interchange on your statement. You see the total transaction fee at the provider’s rate, with no breakdown of what went to the card issuer, what went to the card scheme, and what the provider kept. The PSR’s 2025–2026 scheme and processing fees review is implementing transparency remedies, but those primarily target acquirer-to-scheme pricing rather than what shows up on your merchant statement. To find out what you are paying in interchange today, request a worked IC+ quote from a second provider and compare the effective rates on your actual card mix.
Under IC+, your statement shows interchange paid at cost and then one mark-up line that combines scheme fees and acquirer margin. You can see the interchange component, but you cannot separate the scheme fee from the acquirer’s own profit. Under IC++, used by Adyen, all three components are itemised separately: interchange, scheme fees, and acquirer margin. IC++ gives you the most leverage in future pricing negotiations because you can benchmark each component independently, including challenging scheme fee increases your acquirer might otherwise absorb and pass through quietly.
UK commercial and corporate cards are explicitly excluded from the Interchange Fee Regulation caps that limit consumer card interchange to 0.20% (debit) and 0.30% (credit). Commercial card interchange is set by Visa and Mastercard without a regulatory ceiling and typically runs significantly higher, approximately 1.30%–1.80% depending on card type. On an IC+ contract, you pay that actual interchange cost in full on every corporate card transaction. On a blended contract, the acquirer absorbs the variance but sets the commercial card rate high enough to ensure they still profit across the portfolio. Neither model makes commercial cards cheap. They price the cost differently and hand the bill to different parts of your year.
Growth alone is not enough reason to switch. The right trigger is a combination of: monthly card volume consistently above £8,000–10,000; a card mix that is predominantly UK consumer debit; confidence the volume will remain stable enough to justify a 12-month-plus contract; and a worked quote from an IC+ provider that shows actual savings after all monthly fees, authorisation fees, MMSC floors, and any setup costs are included. Before you request quotes, ask your current PSP for a card mix breakdown; most will supply one. That breakdown is the most important input in the calculation, and it is the one most businesses have never seen.
Most traditional acquirer contracts include a monthly minimum service charge of £10–£30. If your card processing fees for the month do not reach that floor, you pay the shortfall regardless of what you actually processed. A business that closes for two weeks in August, runs a summer-only operation, or has genuinely uneven trading across the year can end up paying MMSC in every quiet month for the duration of a multi-year contract. Flat-rate providers charge nothing in a zero-transaction month. If your trading is seasonal or unpredictable, include MMSC in your total cost of ownership calculation and model the quiet months, not just the peak.
Methodology and Disclosure
How we did this. We built this guide from the published UK pricing of the providers named (Stripe, Square, SumUp, Teya, Tyl by NatWest, Dojo, Elavon, Worldpay and Adyen), the UK Interchange Fee Regulation caps administered by the Payment Systems Regulator (0.20% on consumer debit, 0.30% on consumer credit), and the PSR’s card-acquiring (MR18/1.8) and scheme & processing fees (CP25/3) market reviews. The worked example models one defined business — £20,000/month, a £45 average transaction, a 70% debit / 20% credit / 10% commercial card mix — so the three models can be compared on total monthly cost rather than headline rate.
What this guide does not do. IC+, IC++ and enterprise blended rates (Dojo Flex, Elavon bespoke, Worldpay enterprise, Adyen) are negotiated, so the figures shown are indicative, not quotes — confirm your own rate, monthly fees, MMSC and contract term in writing before signing. Interchange caps, scheme fees and published tariffs change, and the PSR’s 2026 remedies may shift them further; verify the current numbers with the provider or the card schemes. We last checked the figures in this guide against provider and regulatory sources in May 2026.
Disclosure. BusinessExpert is reader-supported. Some links on this page are affiliate links — Square and SumUp — and if you click through and buy, we may earn a commission at no extra cost to you. The other provider links are direct, non-affiliate links. Affiliate relationships never affect our editorial assessments, the rates we report, or which providers we name. See our editorial policy.