Interchange-plus vs blended pricing: which one actually saves a UK merchant money?
Every UK card processing quote uses one of two pricing models — interchange-plus or blended. They look similar on the surface and produce very different bills. This guide walks through the difference in plain English, with a worked example in pounds, and a short script for spotting which model a quote is actually using.
The two pricing models in 60 seconds
Interchange-plus pricing breaks every transaction into three explicit costs: the interchange fee paid to the card-issuing bank, the scheme fee paid to Visa or Mastercard, and the acquirer's margin on top. The merchant sees all three on the statement.
Blended pricing rolls all three into a single rate. The merchant sees something like '1.65% per transaction' and pays that on everything, regardless of card type or the actual underlying cost.
Interchange-plus is more transparent. Blended is simpler to quote. The transparency is almost always cheaper, because it forces the acquirer to compete on the only number they actually control — their margin.
A worked example: £100,000/month UK merchant
Consider a UK convenience-store merchant taking £100,000/month in card payments, mostly UK consumer debit, with about 10% credit and a small commercial card mix.
Under typical interchange-plus pricing, the merchant pays 0.20% interchange on debit, 0.30% on credit, around 0.04% in scheme fees, and 0.25% acquirer margin. Total per-transaction cost: roughly £790/month. Add a £20 terminal rental and £5 PCI fee — the total monthly bill lands near £815, an effective rate of 0.82%.
Under typical blended pricing for the same merchant, the headline rate might be 1.20% on all UK consumer cards plus 2.50% non-qualified on commercial and international cards. The merchant pays roughly £1,300/month in transaction costs plus the same £25 in fixed fees — an effective rate of 1.33%.
Same merchant, same transactions, same acquirer in theory. The blended contract costs £515/month more — £6,180/year — purely because of the pricing model.
Why blended pricing costs more
Blended pricing only makes sense for the acquirer if the blend lands above the merchant's true cost. The acquirer is selling certainty (a fixed headline rate) in exchange for a margin they don't have to disclose.
On a low-margin commodity industry, blended is rarely the cheaper option for the merchant. It's almost always cheaper for the acquirer, because the merchant can't see what's interchange and what's margin — so they can't negotiate the margin separately.
There are edge cases where blended can be competitive — very small merchants under £5,000/month who pay so little in absolute terms that the simplicity is worth the markup, or merchants with extremely consistent card mixes where the blend is genuinely close to the underlying cost. For everyone else, interchange-plus wins.
How to spot which model a quote is using
Read the quote and look for three signals.
Signal one: 'plus' language. If the quote says 'interchange + 0.25%' or 'IC+' or shows separate interchange, scheme and margin lines, it's interchange-plus.
Signal two: a single headline rate. If the quote says '1.20% on all card transactions', it's blended.
Signal three: non-qualified or tiered rates. If the quote mentions 'qualified', 'mid-qualified', 'non-qualified' tiers, or different rates for different card types without explaining why, it's tiered pricing — a variant of blended that almost always lands above interchange-plus.
If the quote isn't clear on which model it's using, ask the acquirer or consultant directly. The answer should take under 30 seconds. If it doesn't, that itself is information.
When blended actually makes sense
There are three honest cases for blended pricing.
Very small merchants (under £3,000/month in card volume) where the per-transaction admin cost matters more than the rate, and the absolute pound difference between models is tiny.
Very simple businesses with extremely consistent card mixes where the blend has been priced fairly against actual cost — for example, a single-product e-commerce merchant that only takes consumer debit cards from UK customers.
Merchants who explicitly value simplicity over savings and want one number on the invoice. This is a legitimate preference, but it should be a conscious trade-off, not an accidental one driven by the acquirer's preferred model.
The takeaway
Interchange-plus is almost always cheaper for UK SME merchants doing more than a few thousand pounds a month in card volume. Blended is simpler to quote and easier for the acquirer to defend the margin on.
If you're a consultant, lead with interchange-plus and explain the model in 60 seconds. If you're a merchant, demand it. Either way, the worked example above is the conversation — show the £6,180/year difference and the rest of the discussion gets a lot easier.
Frequently asked questions
Is interchange-plus always cheaper than blended pricing?
For UK SME merchants processing more than a few thousand pounds a month in card volume, interchange-plus is almost always cheaper than blended. The transparency forces the acquirer to compete on margin, which compresses the cost. For very low-volume merchants the difference is too small to matter.
How do I know if my current contract is interchange-plus or blended?
Look at the statement. If interchange, scheme fees and acquirer margin are listed as separate lines, it's interchange-plus. If you see a single per-transaction rate applied to all card volume, with separate 'non-qualified' lines for some transactions, it's blended (often tiered blended).
Can I switch from blended to interchange-plus mid-contract?
Usually only when the contract is up for renewal or you're moving to a new acquirer. Some acquirers will offer to switch mid-contract to retain the merchant — it's always worth asking, especially if the volume has grown since the original contract.
Does interchange-plus mean the merchant pays more sometimes?
On a small number of high-cost transactions — international commercial cards, for example — interchange-plus exposes the full cost where blended would have masked it. Net over the whole month, interchange-plus almost always still costs less because the savings on standard cards more than offset the visible cost of expensive ones.