Merchant acquiring pricing: interchange++, blended rates and hidden costs

A merchant acquiring quote is rarely one number. The price you pay per card transaction is built from interchange, scheme fees and acquirer margin, then layered with per-event charges for authorisations, refunds, chargebacks, currency conversion and more. Two providers can quote a similar headline rate and produce very different monthly costs. This guide breaks down the components, contrasts interchange++ with blended pricing, and gives you a variable-based model so you can compare providers on your own volumes rather than on marketing figures.

Interchange

Interchange is the fee that flows from the acquirer to the card issuer for each transaction. It is set by the card networks and varies by card type, region, channel and merchant category. Within the EU, interchange fees for certain card-based payment transactions are regulated 1. Interchange is a cost that any acquirer passes on; the differences between providers lie in how transparently they show it and what margin they add.

Scheme fees

Scheme fees are charged by the card networks themselves for using their rails and services. They are numerous, granular and can apply per authorisation, per transaction or per event. Because they are set by the networks, they are broadly common across acquirers — but how an acquirer presents them (itemised or absorbed into a blend) differs.

Acquirer margin

The acquirer margin is what the acquirer keeps for its own service and risk. In transparent pricing this is the component you actually negotiate, because interchange and scheme fees are largely outside the acquirer’s control. Providing these payment services sits within a regulated framework 2.

Interchange++ structure

Interchange++ (“IC++”) itemises the three components: interchange, plus scheme fees, plus the acquirer’s markup. You see each element separately, which makes the acquirer margin visible and comparable. The trade-off is complexity: your effective rate varies with your card mix, so it is harder to predict a single percentage in advance.

Blended pricing

Blended pricing charges one rate (often plus a fixed per-transaction fee) regardless of the underlying card mix. It is simple and predictable, but it hides interchange, scheme fees and margin inside one number, so you cannot see what you are paying for or where a provider makes its money. Blended rates can be cheaper for some mixes and more expensive for others.

Fixed and percentage charges

Most pricing combines a percentage of transaction value with a fixed amount per transaction. The fixed component matters most for low-value payments, where it can dominate the percentage. When comparing providers, always separate the percentage and fixed elements rather than collapsing them.

Cross-border and currency charges

Transactions where the card and merchant are in different regions often attract additional charges, and card-mix differences (for example more commercial or non-EEA cards) change interchange. If you accept international customers, these charges can be a large share of cost — see comparing cross-border payment providers.

Authorisation charges

Some providers charge per authorisation attempt, separately from the charge on a successful transaction. High retry or pre-authorisation volumes can make this meaningful. Ask whether declined and pre-authorisation attempts are charged.

Refund charges

Refunds may carry their own fee, and the original transaction fee may or may not be returned when you refund. High-refund businesses should model this explicitly, because refund economics can differ sharply between providers.

Chargeback charges

A chargeback typically carries a per-case fee regardless of outcome, plus operational cost to respond. Understand the fee, the dispute process and whether representment costs extra. Chargeback-heavy sectors feel this acutely.

Account updater and token charges

Services that keep stored card credentials current, or that tokenise cards, may carry per-card or per-update fees. For subscription and stored-credential businesses these recur and add up. Token portability also matters if you may switch providers — see the payment gateway vs PSP vs acquirer vs orchestration guide.

Minimum commitments

Providers may impose monthly minimums or platform fees. Below your expected volume these dominate the effective rate; a low percentage with a high minimum can be expensive for a small merchant. Model minimums against realistic early-stage volume, not steady-state.

Reserves

An acquirer may hold a reserve — a rolling or fixed amount withheld against future chargebacks or refunds. Reserves tie up cash and change the effective cost of the relationship even though they are not strictly a fee. Confirm the reserve model, size and release terms.

Payout and settlement fees

Settling funds to your bank account may carry fees, and settlement timing (daily, delayed, or with a rolling hold) affects your working capital. Ask about settlement frequency, any per-payout fee, and currency of settlement.

FX

If you settle in a currency different from the transaction currency, a conversion spread applies. As with cross-border payouts, understand the execution model and spread rather than a single rate. This is separate from the card network’s cross-border charges above.

Effective-rate formula

Model your effective rate with variables instead of comparing quotes. For a period with total card volume V across N transactions, define:

• interchange cost I (varies with card mix)
• scheme fees S
• acquirer margin rate m and fixed per-transaction fee f
• refund cost R, chargeback cost C, and other per-event charges O

An approximate total cost is:

Total ≈ I + S + (m × V) + (f × N) + R + C + O
Effective rate ≈ Total ÷ V

Add monthly minimum M as max(0, M − variable fees) and include the cost of any reserve B held at internal cost of capital c over time t as B × c × t.

Sample calculation using variables

Suppose a month has volume V and N transactions. Provider A quotes interchange++ with margin mₐ and fixed fee fₐ; Provider B quotes a blended rate b. Compare:

Cost_A ≈ I + S + (mₐ × V) + (fₐ × N) + event charges
Cost_B ≈ (b × V) + (fixed_B × N) + event charges

Populate I and S from each provider’s reported card mix and your event volumes. The provider with the lower headline number is not automatically cheaper once N, refunds and chargebacks are included.

Pricing components comparison

Component	Interchange++	Blended
Interchange	Itemised	Hidden in rate
Scheme fees	Itemised	Hidden in rate
Acquirer margin	Visible, negotiable	Not separable
Predictability	Varies with card mix	Single rate
Comparability	High	Low
Best suited to	Merchants optimising cost	Merchants wanting simplicity

Pricing-data request template

Ask every provider for the same inputs so your model is populated consistently:

• Interchange and scheme fees itemised or absorbed (state which)
• Acquirer margin rate and fixed per-transaction fee
• Authorisation, refund and chargeback fees
• Cross-border and currency-conversion charges
• Account updater, tokenisation and other recurring per-card fees
• Monthly minimum or platform fee
• Reserve model, size and release terms
• Settlement frequency and any payout fee

Provider selection checklist

• Pricing model identified as interchange++ or blended for each provider
• Acquirer margin isolated where the model allows
• Fixed and percentage components separated
• Refund, chargeback and authorisation fees captured
• Cross-border and FX charges modelled for your card mix
• Recurring token/account-updater fees included
• Minimum commitments modelled at early-stage volume
• Reserve and settlement terms reviewed with finance

Questions to ask providers

• Is this interchange++ or blended, and can you itemise interchange, scheme fees and your margin?
• What is your fixed per-transaction fee, and does it apply to declines?
• What are the refund and chargeback fees, and is the original fee returned on refund?
• How are cross-border and currency-conversion charges applied?
• Are there token, account-updater or other recurring per-card fees?
• Is there a monthly minimum or platform fee?
• Do you require a reserve, and how is it sized and released?
• How often do you settle, in which currency, and at what fee?

Common failure modes

• Comparing headline rates without modelling per-transaction fixed fees and event charges.
• Choosing blended pricing for simplicity, then losing visibility of rising card-mix costs.
• Ignoring refund and chargeback fees in high-return or disputed sectors.
• Overlooking minimum commitments that dominate cost at low volume.
• Missing a reserve that quietly ties up working capital.

What this does not cover

This guide does not set or predict prices, quote interchange or scheme fees, assess any specific provider, or make any compliance determination. Interchange and scheme fees change and vary by many factors; obtain current figures from your provider. It complements — but does not replace — professional financial and legal advice.

FAQ

Is interchange++ always cheaper than blended?

No. Interchange++ makes costs transparent and often benefits merchants who optimise, but for some card mixes and volumes a blended rate can be simpler and comparable. Model both on your own numbers.

Can the acquirer control interchange?

Largely no. Interchange is set by the networks and, for certain card transactions in the EU, regulated 1. What you negotiate with an acquirer is mainly its margin.

Why do cross-border transactions cost more?

Because different card mixes and regions can attract higher interchange and additional network charges, and settling in another currency adds a conversion spread. Model these separately for international volume.

What is a reserve and does it count as a fee?

A reserve is money the acquirer withholds against future chargebacks or refunds. It is not strictly a fee, but it ties up cash, so include its cost of capital in your comparison.

How should I compare two quotes fairly?

Populate one variable-based model with each provider’s itemised inputs and your real volumes, transaction counts, refunds and chargebacks, then compare the resulting effective rate — not the headline percentages.