Flat-Rate vs Interchange-Plus Pricing: Which is Better?

Choosing a pricing model is one of the most consequential payment processing decisions a business makes. The difference between flat-rate and interchange-plus can mean thousands of dollars per year, but the right choice depends on your specific business profile. This guide explains both models with concrete examples so you can make an informed decision.

How Flat-Rate Pricing Works

Flat-rate pricing charges a single, fixed percentage (and often a per-transaction fee) on every transaction, regardless of card type or how the transaction is processed. Popularized by consumer payment platforms, it offers simplicity at the cost of efficiency.

A typical Canadian flat-rate example:

• In-person transactions: 2.6% + $0.10 per transaction
• Online transactions: 2.9% + $0.30 per transaction

Whether a customer pays with a basic Visa debit card (actual interchange: ~0.10%) or a premium World Elite Mastercard (actual interchange: ~2.4%), you pay the same flat rate. When the actual interchange is much lower than the flat rate, the processor keeps the difference as additional profit.

How Interchange-Plus Pricing Works

Interchange-plus (IC+) pricing passes the actual interchange rate through to the merchant and adds a fixed, transparent markup. The structure looks like this:

• Interchange (actual rate, varies by card type) + fixed markup (e.g., 0.25%) + per-transaction fee (e.g., $0.10)

So if a customer pays with a standard Visa credit card with a 1.3% interchange rate, you pay 1.3% + 0.25% + $0.10 = 1.55% + $0.10. If they pay with a basic debit card at 0.10% interchange, you pay 0.10% + 0.25% + $0.10 = 0.35% + $0.10.

Your statement shows exactly what went to interchange (the issuer), what went to assessment fees (the card network), and what went to your processor. Nothing is hidden. You can read more about what makes up these costs in our guide to understanding credit card fees.

Side-by-Side Comparison

Worked Example: $100,000/Month in Sales

Let us assume a business processes $100,000 per month with the following card mix:

• 40% debit cards (average interchange: 0.10%)
• 45% standard credit cards (average interchange: 1.30%)
• 15% premium rewards cards (average interchange: 2.20%)
• Average effective interchange: (0.40 × 0.10%) + (0.45 × 1.30%) + (0.15 × 2.20%) = 0.04% + 0.585% + 0.33% = 0.955%

This example illustrates why the card mix matters enormously. A business with 40% debit volume is significantly overpaying under flat-rate pricing because debit interchange is just a fraction of the flat rate they are charged.

When Flat-Rate Makes Sense

Flat-rate pricing genuinely suits some businesses:

• Very low volume: If you process under $5,000–$10,000/month, the simplicity and lower account fees of flat-rate often outweigh the rate efficiency of IC+.
• Highly unpredictable card mix: If you primarily accept premium cards (e.g., a luxury goods retailer with corporate clients), the cap at the flat rate can occasionally work in your favour.
• Startups and testing phases: When you are just starting out and need simple, predictable costs with no monthly fees, flat-rate provides a low-friction entry point.
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• Very high average ticket with primarily premium cards: If nearly all your customers use premium rewards cards, the flat rate may not cost you significantly more than IC+.

When Interchange-Plus Saves Money

IC+ pricing is advantageous for most established businesses:

• Medium to high volume: Once you are processing $10,000+/month, the rate savings from IC+ typically outweigh any higher monthly account fees.
• Mixed card environments: If customers pay with a variety of card types, IC+ ensures you pay appropriately for each type — especially low-cost debit transactions.
• B2B merchants with corporate cards: Combined with Level 2 data submission, IC+ pricing allows you to benefit from significantly reduced corporate card interchange rates.
• Businesses optimizing their processing: If you are implementing best practices like daily batching, AVS checks, and chip + PIN, IC+ ensures those optimizations reduce your actual costs.

What About Tiered Pricing?

A third model — tiered pricing — is still common, especially from traditional bank-affiliated processors. Under tiered pricing, transactions are grouped into "qualified," "mid-qualified," and "non-qualified" tiers, each with different rates. The processor decides which tier each transaction falls into based on proprietary criteria.

Tiered pricing is generally the least favourable for merchants. The tier criteria are often opaque, many transactions are downgraded to mid- or non-qualified rates at the processor's discretion, and you have no visibility into why you are paying a particular rate. If your processor uses tiered pricing, requesting a switch to IC+ is almost always worth investigating.

The Decision Framework

Use these questions to determine which model suits your business:

1. Do you process more than $10,000/month? If yes, IC+ is likely better.
2. Do more than 20% of your transactions come from debit cards? If yes, IC+ saves significantly on those transactions.
3. Do you serve other businesses and need to process corporate cards? If yes, IC+ with Level 2 data is essential.
4. Do you want to implement processing optimizations and actually benefit from them? If yes, you need IC+.
5. Is absolute simplicity and predictability your top priority and volume is low? If yes, flat-rate may be acceptable.

TIB Finance offers interchange-plus pricing with full statement transparency so you always understand exactly what you are paying. To understand more about how interchange rates are set and how to qualify for lower rates, read our guide on interchange rates explained.