Flat-rate vs. interchange-plus: which fits a small store

Small stores mostly see two credit card processing pricing models. Flat-rate charges the same percentage on every card sale. Interchange-plus passes through the actual cost of each card and adds a fixed markup on top. Flat-rate is easier to predict; interchange-plus shows you where the money goes. The right pick depends on your volume and your patience for detail.

Neither is a trick. They're just different trades between simplicity and visibility, and it helps to see the same sale priced both ways.

How does flat-rate pricing work?

One rate covers everything. Say the flat rate is 2.6% plus ten cents per transaction; that's an invented number for illustration, not a quote. A $10 sale costs 36 cents no matter what card the customer used. A premium rewards card, a plain debit card, same charge to you.

That predictability is the appeal. You can figure your card costs on a napkin, and the statement is short. The catch hides in the averaging. Underneath, some cards cost the processor much less than others, and the flat rate is set high enough to cover the expensive ones. When your customers mostly pay with low-cost debit cards, you're paying premium-card prices for economy-card transactions.

How does interchange-plus work?

You pay the true cost of each card, meaning the interchange fee that goes to the card-issuing bank plus the small network assessments, and then a fixed markup to the processor, something like a quarter point plus a nickel per transaction, again invented for illustration. Cheap card, cheap total. Expensive card, expensive total. The markup stays constant either way.

The gain is honesty: you can see exactly what the processor earns. The cost is a longer statement, because every interchange category your customers' cards touched gets its own line. If you're the type who reads statements, it's the model that rewards you. If statements go straight into a drawer, the visibility is wasted on you, and there's no shame in admitting that.

What about tiered pricing?

There's a third model you'll run into. Tiered pricing sorts your sales into buckets, often labeled qualified, mid-qualified, and non-qualified, each with its own rate. The processor decides which bucket each transaction lands in, and the definitions live in fine print.

Honestly, this is the hardest model for a store owner to audit. The teaser rate you were quoted applies to the qualified bucket, and a surprising share of everyday transactions can land in the pricier ones. If you're offered tiered pricing, ask exactly what pushes a sale out of the qualified tier, and get the answer in writing.

So which fits a small store?

If your card volume is modest and you value knowing your cost at a glance, flat-rate serves you fine. If your volume is growing and you'll actually read the statement, interchange-plus usually deserves the look, because visible markup is markup you can question.

One practical move settles most of the debate: bring a recent statement to any provider you're considering and ask them to price that same month both ways. Ten minutes of arithmetic beats a season of wondering, and a provider that won't do the exercise in front of you has answered a different question. Your own card mix, not a brochure, is the deciding vote.

There's also a different path worth knowing: a cash discount program, where posted prices reflect the cost of card acceptance and customers who pay cash get a discount at the register. It reframes the fee question instead of just repricing it, and NRS Pay offers plans built around it alongside its other options.