Interchange-plus vs flat-rate pricing, explained.

Every card you accept has a wholesale cost — interchange — set by Visa, Mastercard, Discover, and American Express and paid to the bank that issued the customer's card. No processor discounts it. The pricing model your processor uses is simply how they wrap their own markup around that wholesale cost. That choice decides whether you can see what you pay, and often how much you pay. The two models you'll be quoted are interchange-plus and flat-rate.

What interchange-plus pricing is

Interchange-plus — sometimes called cost-plus — passes interchange straight through to you at cost, then adds the processor's markup as a separate line: interchange, plus a fixed percentage and a per-transaction fee. On your statement you can see the wholesale portion and the markup portion side by side. That transparency is the whole point: a markup you can see is a markup you can question, and it doesn't grow just because a ticket is large.

What flat-rate pricing is

Flat-rate charges one blended percentage — often plus a small fixed fee — for every card, no matter what the underlying interchange was. It's simple and predictable, which is why it's the default for many pop-up and very-low-volume sellers. The catch: interchange and markup are fused into a single number, so you can never tell how much of each dollar is wholesale cost versus the provider's margin. When a card carries low interchange, the provider keeps the difference; you never see it.

A close cousin is tiered pricing ("qualified / mid-qualified / non-qualified"), which sorts cards into buckets whose definitions the processor controls. It shares flat-rate's core problem — you can't see the true cost — with the added downside that cards can be quietly down-graded into a more expensive tier.

Side by side

Which one actually costs less?

The honest answer is: it depends on your volume and card mix, and the only way to know is to compare effective rates on a real statement. That said, there's a reliable pattern. Flat-rate's convenience is real at very low volume, where simplicity outweighs a few dollars of hidden markup. But as volume grows, the bundled markup compounds — every large ticket carries the same blended percentage even when its true interchange was low — and interchange-plus usually pulls ahead, because you're only paying a transparent, fixed markup over wholesale.

The trap is that flat-rate feels cheaper because the number is small and single. Compute your effective rate — total fees ÷ total volume — and the comparison stops being a feeling. Our guide to lowering processing fees walks through that calculation step by step, and Lifted Payments vs Square runs the crossover math against a real published flat-rate schedule.

Where interchange-plus really pays: commercial cards

One advantage flat-rate structurally can't match: Level 2/3 optimization. Business, corporate, purchasing, and government cards qualify for lower interchange when the transaction carries extra data — and on interchange-plus, that lower cost passes to you. On flat-rate, the same card is charged the same blended rate either way, so the savings evaporate. If any meaningful share of your customers pay on commercial cards, this alone can be the deciding factor — see Level 2/3 processing and our B2B credit card processing guide.

How to choose — and how to compare fairly

• Compute your effective rate. Total processing fees ÷ total card volume for one month. This neutralizes the marketing.
• Ask to see the markup itemized. A processor that won't show the split is telling you something.
• Weigh your card mix. Heavy on commercial cards? Interchange-plus with Level 2/3 is likely the bigger lever.
• Check for lock-in. Long contracts and early-termination fees are how a bad flat rate keeps you.

Lifted Payments quotes interchange-plus after reading one recent statement — wholesale interchange at cost, a clear disclosed markup, and commercial cards optimized on Level 2/3. There's no application fee, and if we can't beat your current rate, we'll tell you.