Quick Answer: Interchange is a fee paid by a merchant’s bank to a cardholder’s bank every time a card transaction is processed. It is set by the card networks (Visa, Mastercard) and typically ranges from 0.10% to 3.50% of the transaction amount plus a flat per-transaction fee. For most mid-market merchants, interchange is the single largest component of their total payment processing cost.
If you’ve ever looked at a processor statement and wondered why the fees seem so high, or why they change month to month even when your sales volume stays flat, interchange is usually at the center of the answer.
Most merchants treat card processing fees as a fixed cost of doing business. The bill comes in, it gets paid, and nobody asks too many questions. But interchange isn’t fixed. It moves based on what kinds of cards your customers are using, how you’re processing transactions, and dozens of other factors your processor likely isn’t surfacing for you.
Understanding interchange is the first step to understanding what you’re actually paying and why.
What Exactly Is an Interchange Fee?
Every time a customer pays with a credit or debit card, money moves between two banks: the merchant’s bank (called the acquiring bank) and the cardholder’s bank (called the issuing bank). The issuing bank takes on risk in that transaction,credit risk, fraud risk, rewards liability, and interchange is how it gets compensated for that risk.
The acquiring bank passes that cost along to you, the merchant, usually bundled into your total processing fee. What your processor charges you is typically interchange plus a markup, the markup is how they make money.
Here’s the key: interchange isn’t a single number. It’s a rate table published by Visa and Mastercard — with hundreds of different rate categories depending on the type of card, the type of transaction, and how the transaction was processed.
Who Sets Interchange Rates?
The card networks — primarily Visa and Mastercard — set interchange rates. Discover and American Express have their own separate rate structures.
Rates are published publicly, but the tables are extensive. Visa’s interchange rate table alone contains over 60 distinct categories. Mastercard’s is similarly complex. These rates are updated twice a year (typically April and October), which is one reason your processing costs can shift even when your business hasn’t changed.
What Is an Interchange Category and Why Does It Matter?
When a transaction processes, it gets assigned to an interchange category. That category determines the rate you pay. The category is based on several factors:
- Card type (consumer debit, consumer credit, rewards, corporate, government, prepaid)
- Industry type (your MCC, Merchant Category Code)
- How the transaction was authorized (card present vs. card not present)
- Whether the full card data was captured and transmitted correctly
- How quickly the transaction was settled
When a transaction qualifies for the category the card network intends, it processes at the expected rate. When something goes wrong, a missing data field, a delayed settlement, a manually keyed entry, the transaction can ‘downgrade’ to a more expensive category. Downgrades are one of the most common sources of avoidable interchange cost for mid-market merchants.
How Does Interchange Relate to What My Processor Charges Me?
Your processor doesn’t set interchange, but they decide how to pass it through to you. There are three common pricing models:
- Interchange-plus pricing: You pay the actual interchange rate for each transaction, plus a fixed markup from your processor. This is the most transparent model, you can see exactly what the card networks charged vs. what your processor charged.
- Tiered pricing: Your processor groups transactions into ‘qualified,’ ‘mid-qualified,’ and ‘non-qualified’ buckets, each with its own flat rate. You lose visibility into the underlying interchange rates, and transactions can quietly shift into more expensive tiers.
- Flat-rate pricing (e.g., Stripe, Square): You pay a single flat rate (e.g., 2.9% + $0.30) regardless of the card type or transaction category. Simple, but expensive for most mid-market merchants because you pay the same on a cheap debit card as on a premium rewards card.
For most merchants processing meaningful card volume, interchange-plus pricing offers the clearest picture of your true costs and the most opportunity to optimize.
What Do Interchange Fees Cost the Average Mid-Market Merchant?
The answer varies significantly based on your industry, your card mix (what types of cards your customers use), and how your transactions are processed. But some general benchmarks:
- For retail merchants with primarily in-person debit transactions: effective interchange rates often fall in the 0.30%–0.80% range
- For ecommerce merchants: effective interchange rates typically run 1.65%–2.50%, reflecting the card-not-present premium and heavier rewards card usage
- For merchants with a high mix of corporate or premium rewards cards: effective rates can exceed 2.50%
Based on Optimized Payments’ work with 700+ client engagements, merchants who haven’t audited their interchange costs in the past 12 months typically find between 10 and 30 basis points of avoidable cost, the result of downgrades, missed optimization opportunities, or suboptimal processor settings.
On a $50 million payment volume, 20 basis points is $100,000 per year.
How to Optimize for Lower Interchange Fees
Understanding interchange is the starting point. But for merchants processing meaningful card volume, the more valuable question is: how much of what you’re paying is actually avoidable?
The answer, for most mid-market merchants, is more than you’d expect. Interchange isn’t purely a fixed cost, it responds to how you process transactions, what data you submit, and how your payment infrastructure is configured. Here are the highest-impact levers.
Verify your Merchant Category Code (MCC) Every merchant is assigned an MCC by the card networks — a four-digit code that identifies your business type and influences which interchange rate categories apply to your transactions. If your MCC is misclassified, you may be paying higher rates across your entire transaction volume without knowing it. Merchants with multiple business lines should also explore whether splitting MCCs across those lines creates a more favorable rate structure for each.
Implement Address Verification Service (AVS) AVS compares the billing address submitted at checkout against what the card issuer has on file. For card-not-present transactions, implementing AVS provides an authentication signal that reduces fraud risk — and Visa and Mastercard both actively incentivize its use through lower interchange rates for qualifying merchants. It also reduces the likelihood of fraud-related downgrades on ecommerce and phone transactions.
Settle transactions daily Every authorization has a validity window. For retail merchants, transactions must settle within 24 hours to qualify for the lowest interchange categories; for ecommerce merchants, the window is 7 days for Mastercard and 30 days for Visa, though best practice is to settle when the order ships. Transactions that fall outside these windows downgrade to more expensive categories automatically. Automating your batch close process is one of the simplest and highest-ROI fixes available to most merchants.
Submit Level 2 and Level 3 data for B2B transactions If a meaningful share of your customers are businesses paying with corporate or purchasing cards, Level 2 and Level 3 data submission is likely your single largest optimization opportunity. Level 3 data — purchase order numbers, line-item detail, tax amounts — signals to the card networks that the transaction is a verified B2B purchase, qualifying it for significantly lower interchange rates. Reductions of up to 145 basis points per transaction are possible for merchants who aren’t currently submitting this data.
Analyze and manage your card mix Not all cards cost the same to accept, and understanding which payment methods your customers actually use gives you the foundation to make smarter decisions. If a disproportionate share of your volume runs on premium rewards or corporate cards, you have a different optimization problem than a merchant whose customers primarily use consumer debit. Knowing your card mix — and how it’s shifting over time — turns interchange from an invisible cost into a managed one.
Ready to go deeper? Download The Merchant’s Guide to Lowering Interchange Fees — a practical playbook covering every major interchange optimization strategy, built for mid-market merchants who want to move from understanding their costs to actively reducing them.
Interchange is one of those costs that rewards attention. For merchants who understand how it works — what drives the rates, what causes transactions to downgrade, where the optimization levers are — it stops being a fixed expense and starts being a managed one. The gap between what most mid-market merchants currently pay and what they should pay is rarely the result of bad luck or bad contracts. It’s usually the result of limited visibility. Once you can see your interchange costs clearly, broken down by card type, by category, by processor, the path to reducing them becomes straightforward. That’s where the work starts.