The short answer
There is no published volume at which interchange-plus always wins. It is worth modelling when your volume has grown, when your average ticket is large, when much of your volume is debit, or when you take business, corporate or purchasing cards. Compare the two structures on your own statement: price the same month under interchange-plus using your actual card mix, add the quoted markup and every fixed fee, and compare the two effective rates.
What you are actually comparing
A flat rate is one price per transaction type that bundles interchange, network fees and the provider's margin into a single number. Interchange-plus passes interchange and network fees through at cost as separate amounts and adds a stated markup, usually a percentage quoted in basis points plus a per-transaction fee. Neither structure is cheaper by definition. Flat rate is a fixed price for a variable cost, which means the provider keeps the difference when your sales land in cheap programs and absorbs it when they land in expensive ones. Interchange-plus moves that variability back to you and makes it visible.
The spread you are exposing yourself to
Visa's US schedule effective April 18, 2026 shows how far apart the programs sit for the same card type. Under interchange-plus, a month with more keyed or online sales costs you more; under a flat rate it does not. That is the trade.
| Fee program | Rate |
|---|---|
| CPS/Retail, Debit (exempt Visa Check Card) | 0.80% + $0.15 |
| CPS/Card Not Present, Debit (exempt) | 1.65% + $0.15 |
| Regulated Visa Check Card | 0.05% + $0.21 |
| Retail Credit — Performance Threshold I (Traditional Rewards, All Other Products) | 1.43% + $0.10 |
| Non-Qualified Consumer Credit (all consumer credit products) | 3.15% + $0.10 |
| Purchasing and Corporate T&E — Commercial Product 3 | 1.75% + $0.10 |
| Purchasing and Corporate T&E — Non-Qualified | 2.95% + $0.10 |
How to run the comparison
Take one recent month's statement and note total card volume, transaction count and total fees. Ask the interchange-plus provider to price that exact month: interchange and network fees for your actual card mix, plus the markup and every fixed monthly fee. Divide each total by your volume to get two effective rates. Repeat with a second month if your sales are seasonal, and with a third if your card mix moves. Two rules keep the exercise honest. Insist on a real month rather than a model month, and insist that every fixed fee is in the total — a markup quoted in basis points with the monthly fees left out is not a price.
Debit volume is the most common reason the answer flips
Debit interchange is far below the flat rates most bundled plans charge, which is why a debit-heavy business is often the clearest case for passing costs through. The Federal Reserve publishes what issuers actually received: across all networks in 2024 the average debit interchange fee was $0.34 on an average transaction value of $46.32, or 0.73 percent. Covered transactions averaged $0.23 on $48.95, or 0.47 percent; exempt transactions averaged $0.51 on $42.27, or 1.21 percent, and were 39.3 percent of transactions by number. On a flat rate you pay the same whichever of those a sale was. That is not a scandal — it is what a fixed price means — but it is worth quantifying before you decide.
Why average ticket matters
Per-transaction fees weigh more on small sales. At a $9 average sale a $0.10 per-item fee is about 1.1 percent of the sale before any percentage applies, so compare the per-item fee as closely as the percentage. On large tickets the percentage dominates instead, and a regulated debit sale at 0.05% + $0.21 costs very little as a share of a large sale. Work out which regime you are in before you weigh a quote: the same markup can be excellent for one business and poor for another.
Why business cards change the answer
Visa prices purchasing, corporate and business cards in their own tables, well above consumer retail programs. On interchange-plus the program a sale qualifies for appears on your statement, so you can see where your B2B volume is landing and act on it. On flat-rate pricing you may pay the same rate whatever program applied, and the difference stays with the provider. If a meaningful share of your volume is on business cards, that alone is a reason to model the change.
Questions to settle before you sign
Ask whether the markup is guaranteed for the term or can be changed on notice, and what notice. Ask whether network fees and assessments are passed through at cost and shown as separate lines. Ask which fixed fees apply and whether any are new. Ask whether the change requires new hardware or a gateway change, and who pays. Ask whether you can move back, and at what cost. Get the answers in the agreement rather than in an email, because the agreement is the part that binds.
About the rate tables on this page: Visa is the only card network that publishes a public US merchant interchange schedule, so the rate tables on this site are Visa-only. Mastercard, American Express and Discover do not publish an equivalent US merchant schedule, and their rates are neither shown above nor implied by these figures. Ask your processor for the rates that apply to each network on your account.
Key takeaways
- No single volume threshold applies to every business
- Compare both structures on the same real statement, fixed fees included
- Interchange-plus moves cost variability from the provider back to you
- Debit-heavy and business-card-heavy volume are the strongest cases for switching
- Small tickets make the per-item fee matter; large tickets make the percentage matter
- Settle markup, pass-throughs, fixed fees and reversibility in the agreement
Related guides
Sources
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