Interchange-Plus vs Blended Pricing: When Each Wins and What You Actually Pay

The pricing model your PSP uses is not neutral. It decides whether the margin between what you pay and what your PSP earns is visible, negotiable, and benchmarkable — or buried in a single number that neither side discusses.

Blended pricing and interchange-plus (IC+) are the two dominant models for card acceptance pricing. Both pay the same underlying costs — interchange to the issuing bank, scheme fees to Visa or Mastercard, acquirer margin to your PSP. The difference is in how those costs are presented, which determines what you can see, what you can negotiate, and whether switching PSPs is easy or expensive.

What Blended Pricing Actually Is

Blended pricing presents a single flat rate — Stripe’s standard 2.9% + $0.30 in the US, Square’s 2.6% + $0.10 for card-present, and similar from most entry-level PSPs. The rate applies regardless of card type: the merchant pays the same whether the customer uses a basic debit card, a premium rewards credit card, or a corporate purchasing card.

The mechanism that makes this work for the PSP: on low-interchange cards (standard debit, EU consumer credit regulated at 0.20–0.30%), the PSP keeps the difference between the blended rate and the actual underlying cost. On high-interchange cards (premium rewards, corporate, commercial), the PSP absorbs the cost from the low-interchange margin it built up elsewhere. Across a large enough merchant base, the cross-subsidy works.

For an individual merchant, the economics depend on your card mix. Consider a US merchant on 2.9% blended pricing:

• A standard debit card transaction carries roughly 0.05% + $0.22 interchange (regulated under Durbin for large issuers). On a $100 transaction, the PSP collects $2.90, pays ~$0.27 in interchange, and keeps ~$2.63 plus scheme fees. Effective PSP margin: ~2.30%.
• A Visa Signature rewards card carries ~2.10% interchange on the same $100 transaction. The PSP collects $2.90, pays ~$2.10 in interchange, and keeps ~$0.80. Effective PSP margin: ~0.50%.

The same blended rate, opposite economics depending on which card your customer pulls out. At 2.9%, a debit-heavy merchant is significantly overpaying relative to their actual interchange cost.

What Interchange-Plus Looks Like

Under IC+ pricing, interchange and scheme fees pass through at cost. Your statement shows the actual interchange each transaction incurred, the scheme fees charged by Visa and Mastercard, and the acquirer margin separately. The margin is what your PSP actually earns.

A typical IC+ contract reads: interchange at cost + 0.20% + $0.10 per transaction. On that same $100 standard debit transaction:

• Interchange: $0.27 (at cost)
• Scheme fees: ~$0.10
• Acquirer margin: 0.20% + $0.10 = $0.30
• Total: $0.67 — versus $2.90 blended

On the rewards credit card:

• Interchange: $2.10 (at cost)
• Scheme fees: ~$0.14
• Acquirer margin: $0.30
• Total: $2.54 — versus $2.90 blended

The IC+ rate is lower for debit-heavy merchants, higher-cost for premium-credit-heavy merchants, and always transparent about what goes where.

The Real Calculation: What Is Your Theoretical IC+ Cost?

Before deciding whether to push for IC+ pricing, you need an estimate of your actual interchange cost. This requires knowing your card mix — the distribution of card types across your transactions.

The rough calculation:

1. Estimate your blended interchange rate. Take your transaction volume by card type if your PSP reports it. Multiply each segment by the applicable interchange rate for your geography. For US merchants without this data, a reasonable starting estimate for an e-commerce business with a mixed consumer card base is 1.4–1.8% blended interchange.

2. Estimate scheme fees. For a typical US e-commerce merchant with minimal cross-border volume, scheme fees run 0.10–0.20% of volume.

3. Estimate achievable acquirer margin. At $50K–$200K monthly processing volume, realistic IC+ acquirer margins at mid-tier PSPs run 0.25–0.45%. Above $1M, sub-0.25% is achievable. Above $10M, sub-0.15%.

4. Sum the components. Interchange (1.4–1.8%) + scheme fees (0.10–0.20%) + acquirer margin (0.25–0.45%) = 1.75–2.45% estimated IC+ cost for a typical US e-commerce profile.

Compare that against your current blended rate. If the gap is 0.50% or more and your volume is above $50K monthly, the annualised saving is meaningful and the negotiation is worth starting.

When Blended Pricing Is Defensible

Blended pricing is not always the wrong choice. Three scenarios where it may be rational:

Low volume with debit-heavy mix. Below $20K monthly, IC+ is not typically available and the administrative complexity of tracking interchange categories is not worth it. The blended rate is also partially a subsidy — PSPs price their small-merchant offering at a level that covers customer support, dispute handling, and account maintenance that is not volume-proportional.

Predictability over optimisation. For some operators, the variance in IC+ billing creates reconciliation complexity that costs more in staff time than the savings. A single blended rate is easy to forecast and integrate into pricing models.

Premium-card-heavy customer base. If your customers are disproportionately corporate card or premium rewards users — common in B2B SaaS or luxury goods — your blended rate may be cheaper than IC+ because the PSP is implicitly subsidising your high-interchange card mix through other merchants. This is rare and requires verifying your actual card mix, but it happens.

When IC+ Is Clearly Better

IC+ wins when the calculation above shows a gap of 0.50% or more, when you have volume to negotiate meaningful acquirer margin compression, or when you need to accurately model the per-transaction cost of acceptance by card type for pricing or routing decisions.

IC+ also wins in cross-border contexts. When interchange varies significantly by geography — EU consumer credit at 0.30% versus US premium credit at 2.10% — blended pricing either overcharges your EU customers’ card acceptance or forces you to accept unprofitable US premium card economics depending on how the PSP structured the rate. IC+ lets you see and model both.

The final argument for IC+: it makes PSP comparisons precise. Comparing two blended rates requires you to know that the card mix assumption behind each rate is identical — which it rarely is. Under IC+, you can compare acquirer margin directly across PSPs because the interchange and scheme components are identical. It converts a complex multi-variable comparison into a single negotiable number.

How to Push for IC+ Pricing

Most PSPs offer IC+ to merchants above a volume threshold — typically $50K–$100K monthly for Stripe and Checkout.com, with Adyen available on IC+ by default for most merchants who request it.

The conversation framework:

1. Request an itemised processing statement for the last 90 days showing interchange, scheme fees, and acquirer margin as separate line items. If the PSP provides this on request, you already have IC+ reporting — ask to convert the contract to IC+ pricing formally.
2. Calculate your blended interchange from that statement. Use this as your anchor in the pricing conversation.
3. Quote your total volume, card mix, and chargeback ratio as context for the margin offer. PSPs price IC+ acquirer margin primarily on volume and risk, not negotiating skill.
4. Benchmark against published IC+ margins at comparable PSPs. Adyen’s interchange+ pricing, for example, is published in their pricing documentation. Use external benchmarks to anchor expectations.

The acquirer margin under IC+ is the most negotiable component of card acceptance costs — and IC+ pricing is the only way to see it clearly enough to negotiate it.

The Comparison Problem

A persistent practical issue: most operators compare PSPs on headline blended rates without understanding that the rates are not directly comparable. A 2.7% blended rate at PSP A versus a 2.9% blended rate at PSP B may be cheaper or more expensive depending on your card mix and how each PSP priced for their expected customer base.

The only clean comparison methodology:

1. Run the same transaction volume through a theoretical IC+ model using your actual card mix.
2. Get IC+ quotes from each PSP.
3. Compare the acquirer margin component — that is the only variable that differs between PSPs. The interchange and scheme fee components are identical.

Blended pricing makes this comparison impossible by design. That is not necessarily intentional obfuscation — it is a pricing model built for simplicity — but the effect is that operators who accept blended pricing cannot accurately compare their PSP to alternatives. IC+ pricing, whatever its complexity, is the model that enables informed vendor decisions.

The headline rate is not the fee. It is the summary of four layers, one of which is fixed, one semi-fixed, one negotiable, and one often invisible. Knowing which is which is the prerequisite to paying less of all four.