It's not fixed. And for many businesses, it's not small.
How Payment Processing Fees Actually Work
When a customer pays you by card, several parties take a cut before the money reaches your bank account. Understanding who those parties are explains why the fee you see on your statement is structured the way it is.
The interchange fee goes to the bank that issued the customer's card – Visa or Mastercard sets the rate, and the issuing bank collects it. This is the largest component of most processing fees, typically ranging from 1.5% to 2.5% depending on the card type. Rewards cards, corporate cards, and premium credit cards carry higher interchange rates than basic debit cards, which is why you pay more when a customer swipes an Amex Platinum than when they tap a standard debit card.
The assessment fee goes to the card network itself – Visa, Mastercard, American Express, or Discover. This is a smaller slice, typically 0.10% to 0.15%, but it's non-negotiable regardless of your processor.
The processor markup is the fee your payment processor – Square, Stripe, PayPal, your bank's merchant services division – adds on top of interchange and assessment to make their margin. This is the part that varies based on your processor, your pricing model, and sometimes your negotiation.
Most small businesses see a blended rate that combines all three components into a single percentage. When Square shows you 2.6% + $0.10 per swipe, that 2.6% includes interchange, assessment, and Square's margin. The transparency looks clean, but it also means you're paying a flat blended rate regardless of whether the customer is using a low-interchange debit card or a high-interchange rewards card – and you're always paying the higher blended rate.
The Three Pricing Models – and Which One Costs You More
The way your processor structures fees matters as much as the rate itself. There are three primary pricing models, and they favor the processor differently depending on your transaction profile.
Flat-rate pricing is what Square, Stripe, and PayPal use for most small business customers. You pay the same percentage on every transaction regardless of card type – typically 2.5% to 2.9% plus a per-transaction fee. The appeal is simplicity: one rate, no surprises, easy to budget. The drawback is that flat-rate processors make their margin by averaging. When a customer pays with a low-interchange debit card, you still pay the full blended rate – and the processor keeps the spread between what interchange actually cost and what you paid. For businesses with a high proportion of debit transactions, flat-rate pricing is almost always more expensive than the alternatives.
Interchange-plus pricing passes the actual interchange cost through to you, adds a fixed processor markup on top (typically 0.2% to 0.5% plus a small per-transaction fee), and charges you the assessment fee separately. The total is usually lower than flat-rate pricing for most transaction mixes because you're paying actual interchange rather than a blended rate that assumes worst-case card types. The trade-off is variability – your effective rate changes with the mix of cards your customers use, which makes monthly statements more complex to read. Most businesses with meaningful monthly volume – say, $10,000 or more per month in card transactions – are better off on interchange-plus pricing.
Tiered pricing is the least transparent model and the one most likely to cost you more than it should. Processors that use tiered pricing sort transactions into categories – typically "qualified," "mid-qualified," and "non-qualified" – and charge different rates for each tier. The catch is that processors define those tiers themselves, which means they control which of your transactions fall into the higher-cost tiers. Rewards cards, business cards, and any transaction that doesn't meet specific processing criteria often get bumped to mid- or non-qualified rates that can reach 3.5% or higher. Tiered pricing is common among traditional merchant services providers and bank-affiliated processors. If your current processor uses tiered pricing, getting a statement analysis from an interchange-plus provider is worth the time.
The Real Cost When You Do the Math
Consider a small retail business doing $25,000 per month in card transactions at an effective rate of 2.7% (a common flat-rate blended rate for Square or similar). That's $675 per month, or $8,100 per year in processing fees.
If the same business moved to an interchange-plus provider at 0.3% + $0.10 per transaction – and assuming an average interchange rate of 1.7% on their transaction mix and an average transaction size of $45 – the effective rate drops to roughly 2.2%. That's $550 per month, or $6,600 per year. The difference is $1,500 annually, which is not a trivial number for a business running on thin margins.
Now factor in the margin impact. If this business operates at a 30% gross margin, $1,500 in additional processing costs is equivalent to losing $5,000 in revenue. The effect compounds with scale: at $100,000 per month in card volume, that same rate difference costs $6,000 per year and is equivalent to $20,000 in lost revenue at a 30% margin. Looking at processing fees through the lens of their margin-equivalent value makes the scale of the problem harder to dismiss.
The Fees Within the Fees
The headline processing rate is not the only fee on your statement. Most processors layer additional charges that are easy to overlook when you're focused on the per-transaction rate.
Monthly account fees, statement fees, and minimum processing fees add a fixed cost base regardless of transaction volume. A processor charging $25 per month in account fees is adding 0.25% in effective cost to a business doing $10,000 per month, which is meaningful relative to an interchange-plus markup.
Chargeback fees are charged per dispute, typically $15 to $50 per incident. Chargebacks are an operational reality for any business taking card payments, and the fee applies whether you win or lose the dispute. Businesses with higher-risk transaction profiles – subscription billing, high-ticket items, or industries with frequent customer disputes – should factor expected chargeback frequency into their true cost of acceptance.
PCI compliance fees are charged by many processors for maintaining or certifying PCI DSS compliance – the security standards governing how cardholder data is handled. Some processors include PCI compliance support in their service; others charge $100 to $300 per year for it. Non-compliance fees are sometimes charged instead, which is essentially a penalty for not completing the compliance certification. Neither fee is avoidable, but some processors handle it far more transparently than others.
Early termination fees apply if you're on a contract with a traditional merchant services provider and want to switch. These can run $200 to $600 or higher and are the mechanism that keeps businesses locked into unfavorable pricing longer than they should stay. Flat-rate providers like Square and Stripe don't use contracts or termination fees, which is one genuine advantage of their model even if the per-transaction rate is higher.
Practical Ways to Reduce What You're Paying
The most direct action is getting a fee audit. Pull your last three months of processing statements and calculate your effective rate across all transactions and fees. Divide total fees (including monthly and incidental fees) by total card volume. If the result is above 2.5% for a business doing meaningful volume, you're likely paying more than you should.
Request interchange-plus pricing if you're currently on flat-rate or tiered. Many processors will offer this model to businesses with consistent monthly volume – typically $10,000 or more per month. It requires asking; processors rarely migrate customers to lower-cost pricing models voluntarily. If your current processor won't offer interchange-plus, that's a meaningful signal to get competitive quotes.
Encourage lower-cost payment methods where it doesn't create friction. ACH transfers and bank-to-business payments typically cost $0.25 to $1.00 flat per transaction rather than a percentage, which makes them dramatically cheaper than card processing for high-value transactions. For recurring B2B payments, invoicing platforms that support ACH pull are worth evaluating. For consumer businesses, cash discounting – offering a small discount for cash payment – is legal in most US states and some businesses use it to offset card processing costs visibly.
Audit your chargeback exposure. If your chargeback rate is elevated, addressing the operational cause – clearer product descriptions, stronger customer communication, better delivery confirmation, a more accessible refund process – reduces both the chargeback fees and the risk of losing card acceptance privileges if your chargeback ratio exceeds network thresholds.
Review your processor contract annually. Processors sometimes increase rates at renewal without proactive notification. Knowing your current rate and having a recent competitive quote gives you leverage to negotiate at renewal or to make a switch if the pricing has drifted out of line.
What to Avoid
Choosing a processor based on headline rate alone is the most common mistake. A processor advertising 1.5% may apply that rate only to debit transactions and charge 3.5% on rewards cards. Reading the full fee schedule – interchange-plus markup, monthly fees, chargeback fees, PCI fees, and any contract terms – is what tells you the real cost.
Signing long-term contracts with early termination penalties is worth avoiding if you have alternatives. The flat-rate providers have made contracts largely unnecessary for small businesses, and the flexibility to switch without penalty is worth something when pricing needs to change as your business grows.
Ignoring the cost at low transaction volumes is a mistake that catches up with growing businesses. At $2,000 per month in card volume, a 0.5% rate difference costs $10 per month and isn't worth a lot of optimization energy. At $50,000 per month, that same difference costs $250 per month and is worth a conversation with your processor. Know the threshold at which optimization becomes worth your time.
FAQ
What's a good effective processing rate for a small business? For a business doing $10,000 to $50,000 per month in card volume, an effective rate of 2.0% to 2.5% (all-in, including fixed monthly fees divided into the effective rate) is achievable on interchange-plus pricing. Flat-rate pricing typically lands in the 2.5% to 2.9% range. Above 3% is worth investigating regardless of your volume.
Can I negotiate processing fees with my provider? With traditional merchant services providers and bank-affiliated processors, yes – particularly if you have consistent volume, a clean processing history, and a competitive quote from another provider. Flat-rate providers like Square and Stripe don't typically negotiate individual rates; their pricing model is standardized.
Is Square a good choice for a small business? Square is a strong choice for businesses under roughly $10,000 to $15,000 per month in card volume, where the simplicity and no-contract structure outweigh the slightly higher flat rate. Above that threshold, interchange-plus providers typically become more cost-effective, and the savings justify the additional statement complexity.
What's the difference between Visa/Mastercard interchange rates? Interchange rates are set by each card network and vary by card type, merchant category, and how the transaction is processed. Visa and Mastercard publish their interchange rate tables publicly – they're dense documents, but they show exactly what category your business falls into and what base rate applies. Rewards cards, corporate cards, and card-not-present transactions (online or phone orders) all carry higher interchange than basic consumer cards processed in person.
Do I need a separate merchant account? Not necessarily. Flat-rate processors like Square and Stripe aggregate merchant accounts, meaning your transactions flow through a shared account structure rather than a dedicated one. This is fine for most small businesses. Dedicated merchant accounts through traditional processors are typically paired with interchange-plus pricing and offer more stability for higher-volume businesses with established processing history.
📚 Sources
Visa – Interchange Reimbursement Fee Guide: https://usa.visa.com/support/consumer/visa-rules.html
Mastercard – Interchange Rate Schedule: https://www.mastercard.us/en-us/business/overview/support/merchant-interchange-rates.html
Consumer Financial Protection Bureau – Understanding Merchant Processing Fees: https://www.consumerfinance.gov/ask-cfpb/what-is-a-credit-card-interchange-fee-en-2116/
Square – Pricing and Fees: https://squareup.com/us/en/payments/our-fees
Stripe – Pricing Overview: https://stripe.com/us/pricing
