Flat rate or interchange-plus: cheaper for my retail store?

Retail stores pay card fees on nearly every sale. The National Retail Federation says swipe fees are now most retailers' highest operating cost after labor. Whether a flat rate or interchange-plus costs your store less comes down to three numbers: card volume, average ticket and debit share. Here's how to run that math for a retail store.

Which one costs my retail store less?

Interchange-plus usually costs less for a store with steady volume and lots of debit sales. For a very small shop, a flat rate can come out close. In the example below, a store with $40,000 a month in card sales paid about $401 less on interchange-plus. A $5,000-a-month shop came out within $14.

The reason is simple. A flat rate charges every card the same percentage. Interchange-plus passes through each card's wholesale cost, called interchange, plus network fees and a fixed markup. Wholesale costs swing widely by card type, so the store's card mix decides the winner. For the general breakdown of fee layers, see our guide to credit card processing fees.

Why does debit matter so much for a retail store?

Debit is the cheapest card a store takes, and a flat rate hides that. The Federal Reserve's latest payments study found debit cards made up the majority of U.S. card payments in 2024. Debit cards from banks with $10 billion or more in assets are "regulated," and their interchange is capped.

Sources: Visa's rates effective Oct 24, 2026 and Mastercard's rates effective Apr 17, 2026.

On a $40 sale, regulated debit costs about 24 cents in interchange. That's roughly 0.6% of the sale. On a flat rate, the same sale costs the same percentage as a premium rewards card.

The Fed's own data shows the gap. In 2023, regulated ("covered") debit transactions averaged $0.23 in interchange, or 0.47% of the sale. Exempt debit, from banks under $10 billion in assets, averaged $0.52, or 1.21%. In-store debit and prepaid purchases averaged $36.99 that year.

One caution: on Oct 26, 2026, the Eighth Circuit upheld a ruling that struck down the Fed's debit fee rule. The existing cap stays in place for now while the Fed revisits it. Our fees guide tracks what happens next.

What do credit cards cost my store at wholesale?

Credit cards cost more than debit, and rewards cards cost the most. Mastercard's in-store consumer credit rates for 2026 show the spread clearly.

Keying in a card number costs more than a chip read or tap. Visa's debit rows show the same pattern. An in-store exempt debit sale (CPS/Retail) costs 0.80% + $0.15. Keyed in (CPS/Retail Key Entry), it costs 1.65% + $0.15. A store that keys in phone orders or failed swipes pays the higher rate on those sales.

Visa's in-store retail credit rows are also tied to "performance thresholds." Those are measured in millions of transactions and billions of dollars a year. That's big-box territory. An independent store can't negotiate interchange, so the markup is the part worth comparing.

Example: two retail stores priced both ways

This is a hypothetical example, not a quote. It uses the wholesale rates above and these assumptions:

• Card mix by count: 55% regulated debit, 10% exempt debit, 20% basic credit, 15% premium rewards credit.
• Flat rate: 2.6% + $0.15 per sale.
• Interchange-plus: interchange at cost, network fees of about 0.15%, a markup of 0.30% + $0.10 per sale and a $25 monthly fee.

Two things stand out. The busy store's debit-heavy mix keeps its wholesale cost near 1.2%, so a flat rate overcharges it on every debit sale. The small shop's $20 tickets make every per-sale fee weigh more, and the $25 monthly fee eats most of the gap.

Change the assumptions and the answer moves. A shop with more rewards cards narrows the gap. A store with more debit and bigger tickets widens it.

When is a flat rate the better deal for my store?

A flat rate can make sense for a seasonal pop-up, a brand-new store or a shop with very low card sales. It's predictable, and it's easy to read.

It gets expensive as volume grows. A flat rate also stays wherever the provider sets it. When interchange drops, interchange-plus passes the change through. A flat rate doesn't have to.

Before switching, compare the all-in cost: rate, per-sale fee, monthly fees, PCI fees and equipment. A low markup with heavy monthly fees can lose to a flat rate at low volume, as the small-shop example shows.

Do returns change the math for a retail store?

Returns are a bigger issue in retail than in most industries. The NRF and Happy Returns forecast that shoppers would return about 15.8% of 2025 retail sales, nearly $850 billion. Each refund to a card is its own transaction.

Ask any provider how fees on refunds are handled, and check the refund lines on your statement. Voiding a sale before the batch closes is different from refunding it later, so train staff on which to use.

How do I check what my store pays now?

Divide your total monthly processing fees by your total card sales. That's your effective rate. If your statement shows one blended rate and no interchange detail, you're likely on a flat or tiered plan.

Compare that number with your wholesale floor. A debit-heavy store with a $40 average ticket might sit near 1.2% wholesale, as in the example. A big gap between the two is markup. Our guide on how to read your merchant statement shows where each fee appears.

When BP Global Merchant Services fits

BP Global Merchant Services is a Dallas-based, independent Elavon Payments MSP that works with retail stores and other merchants across the U.S. We offer interchange-plus pricing with a fixed, itemized markup and no tiered buckets. Stores that would rather pass card costs on can use dual pricing instead. Our free review breaks out interchange, assessments and markup, then shows in writing what you pay now and what you'd pay. Start with the Free Statement Review.