Interchange plus vs flat rate: which costs less?

The interchange plus vs flat rate choice comes down to one question: do you want to pay what each card actually costs plus a fixed markup, or one blended price on every card? Interchange-plus passes the card network's interchange through at cost and adds the processor's margin on top. Flat rate charges the same percentage and per-transaction fee whatever card the customer uses, and the processor keeps the difference.

Neither model wins every time. Below we define both (including cost-plus and pass-through pricing, which are other names for interchange-plus), run worked examples at four ticket sizes and volumes, show how card mix moves the answer, and spell out when a flat rate is genuinely the better deal. Rates cited are from the Visa and Mastercard schedules in effect in October 2026.

What is interchange-plus pricing?

Interchange-plus means your processor passes through the interchange on each sale at cost and adds a fixed markup that you can see. The Washington State Attorney General's office describes it as pricing where the merchant account provider passes through whatever they are charged plus a flat-fee markup for its services. A quote looks like "interchange + 0.30% + $0.10."

Interchange itself isn't something your processor invents. Mastercard says its interchange rates are established by Mastercard and generally paid by acquirers to card issuers, and that it "has no involvement in acquirer and merchant pricing policies or agreements" (Mastercard). Visa says merchants don't pay interchange directly; they pay a "merchant discount" negotiated with their financial institution (Visa). Interchange-plus simply makes that merchant discount transparent: the network's part on one set of lines, the processor's part on another.

Is cost-plus pricing the same as interchange-plus?

Yes. Cost-plus, pass-through, and interchange pass-through all describe the same structure: card costs passed through at cost, plus a stated markup. A variant some processors sell is interchange plus a flat monthly subscription instead of a percentage markup. It's the same idea with the margin charged differently. Whatever the label, ask two questions: is interchange passed through at exactly the network rate, and are network fees passed through at cost too?

The Washington Attorney General's tip makes one more point worth repeating: until recently, only big businesses could get interchange-plus, and now small and new businesses can request it.

What does an interchange-plus statement look like?

You get a line for each interchange category, with the count, the volume, and the rate, then separate lines for network fees and the markup. Here's an illustrative excerpt using rates from Visa's schedule effective April 18, 2026 (Visa). Your processor's labels will differ.

Every rate on the first three lines can be checked against the published schedule. The regulated debit line reflects the Federal Reserve's Regulation II cap of 21 cents plus 0.05% of the sale, plus a 1 cent fraud-prevention adjustment for eligible issuers (Federal Reserve). Our guide on how to read a merchant statement covers the rest of the page.

What is flat-rate pricing?

Flat rate means one price for every card: a percentage plus a fixed fee per sale, such as 2.7% + $0.10. A regulated debit card and a premium rewards card cost you the same. Ask whether the plan has a different rate for keyed or online sales, and read the rate sheet for other exceptions.

Its strengths are real. You can predict your bill from your sales alone, the statement is short, and many flat-rate plans carry no monthly fee. The cost is that you pay the same percentage on cards that cost the processor very little. Interchange is still inside the flat rate. You just can't see it, so you can't check it.

Interchange-plus vs flat rate at a glance

Which is cheaper? Worked examples at four ticket sizes

To see how ticket size and volume change the answer, we priced four made-up businesses against two made-up quotes. Neither quote is any real processor's price.

• Flat rate: 2.7% + $0.10 per sale, no monthly fee.
• Interchange-plus: interchange at cost, plus 0.30% + $0.10 per sale and a $25 monthly fee.

We gave every business the same card mix, so only ticket size and volume change: 40% regulated debit (0.05% + $0.21, plus the 1 cent adjustment), 10% small-bank debit (0.80% + $0.15), 30% Visa consumer credit "All Other Products" (1.51% + $0.10), and 20% Traditional Rewards (1.65% + $0.10). All sales are dipped or tapped in person and priced at Visa's April 18, 2026 rates. The interchange-plus column leaves out network fees, which an interchange-plus statement lists on their own lines.

Here's the restaurant row worked out. Average interchange per $60 sale is $0.6828: a regulated debit sale costs $0.25, a small-bank debit sale $0.63, an "All Other Products" credit sale $1.006, and a Traditional Rewards sale $1.09, weighted by the mix. Across 700 sales that's $477.96. Add the 0.30% markup ($126.00), 700 per-sale fees of 10 cents ($70.00), and the $25 monthly fee, and you get $698.96. The flat rate is 2.7% of $42,000 ($1,134.00) plus $70.00 in per-sale fees, or $1,204.00.

What the table says:

• At $3,000 a month, it's a near tie. Interchange-plus leads by $5.21, or 0.17% of sales, before network fees, which could easily erase it. Take the simpler option.
• On $8 tickets, flat rate wins. Fixed fees swamp small sales: interchange alone averages 22 cents, or 2.8% of each sale, and the 10 cent markup on 1,500 sales adds $150. Cut the interchange-plus per-sale fee to 3 cents and the total drops to $441.46 (3.68%), $32.54 under flat rate.
• At $60 and $400 tickets, interchange-plus wins by a wide margin: 1.20% and 1.45% of sales. Network fees would have to be larger than that to close the gap, and your statement shows your actual network fees.

Ticket size cuts both ways, then. Small tickets punish any per-transaction fee, and large tickets punish a high percentage. A coffee bar in Seattle should negotiate the per-sale fee hardest. A contractor in Minneapolis should negotiate the percentage. Counter-service businesses should also ask about small-ticket interchange: Mastercard's 2026-2027 schedule prices a Core consumer credit card at 1.65% + $0.02 in its Small Ticket Card Present program (Mastercard), a fixed fee 8 cents lower than its standard Merit III Base rate.

How does card mix change the answer?

Debit-heavy businesses gain the most from interchange-plus, and rewards-heavy ones gain less. Take one $60 regulated debit sale. On the flat rate, it costs $1.72. On the interchange-plus quote, it costs $0.25 in interchange plus $0.28 in markup, or $0.53. A flat rate charges a debit card as if it were a credit card, and that's where most of the gap comes from.

Now swap in a rewards-heavy mix: 10% regulated debit, 30% "All Other Products" credit, 30% Traditional Rewards, and 30% Visa Signature Preferred, which is 2.10% + $0.10 in person.

Interchange-plus still wins, by about half as much. Online sales narrow the gap too, because card-not-present interchange is higher: Visa's Traditional Rewards rate is 1.65% + $0.10 in person and 2.04% + $0.10 card-not-present. Our guides to Visa interchange rates and Mastercard interchange rates list the categories you're most likely to see.

When is flat rate the better deal?

More often than interchange-plus sellers admit. Flat rate is usually the better choice when:

• You process a few thousand dollars a month or less. A monthly fee on the interchange-plus side can wipe out the savings, as the $3,000 row shows.
• Your tickets are tiny and the interchange-plus quote carries a per-sale fee as high as the flat rate's.
• You're brand new or seasonal and want no monthly fees while you find your footing.
• You need to know your card costs to the cent before the month starts.
• Much of your volume is on commercial cards. On a $2,000 Visa commercial card tapped in person, interchange alone is 2.50% + $0.10, or $50.10, per Visa's schedule. Our example interchange-plus quote adds $6.10, for $56.20. The 2.7% + $0.10 flat rate charges $54.10. Read the flat-rate agreement for any exceptions on commercial cards before you count on that.

If one of those fits, don't let anyone talk you into a contract to save a few dollars. Check again when your volume grows.

How does tiered pricing compare?

Tiered pricing sits between the two, and usually not in a good way. Your processor sorts sales into buckets, often called qualified, mid-qualified, and non-qualified, and charges a set rate for each bucket. The Washington Attorney General's tip gives the tell: if your statement shows charges for "qualified," "mid-qualified," or "non-qualified" transactions, you're on a tiered plan.

The problem with tiered pricing is that the bucket rules belong to the processor, so a quote's low qualified rate tells you little about your actual bill. Our guide to tiered pricing works a full month through all three tiers, and our guide to the cheapest credit card processing compares all three models at a $50 ticket.

How do you compare an interchange-plus quote with a flat rate?

Use your own statement, not a sample business.

1. Work out your current effective rate: total fees divided by total card sales, times 100. Our guide to the merchant discount rate shows how.
2. Send the same statement to each processor and ask for that month priced on their terms.
3. For interchange-plus, get the markup as a percentage and a per-sale fee, plus every monthly, annual, and PCI fee.
4. Ask whether network fees pass through at cost or with something added.
5. For flat rate, ask about exceptions for keyed, online, and commercial card sales.
6. Read the contract term and any early termination fee.
7. Compare twelve months of total cost, not headline rates.

Interchange is the same document whoever your processor is, and it doesn't depend on your address. A cafe in Atlanta pays the same Visa rates as one anywhere else in the United States. What differs is the markup and the fees around it. Our credit card processing fees page explains each layer, and if you're weighing a specific flat-rate provider, our comparisons with Square, Stripe, and Helcim go through the details.

Your next step

We price on interchange-plus with no long-term contracts and no cancellation fees, but the right model for you depends on your numbers, and sometimes flat rate wins. Send a recent statement for a free statement review, and we'll price the same month both ways and show you the difference in dollars. If you'd rather talk it through first, contact us.