Interchange-plus, flat-rate, and tiered pricing
The model name matters less than the complete effective cost and how easily you can verify it.
Flat rate: simple, and priced for that simplicity
Flat-rate pricing applies one published structure to broad transaction categories. It can simplify forecasting, but the complete cost still depends on ticket count, channels, card mix, recurring fees, hardware, and software. Verify the provider’s current written rate instead of relying on an example.
Interchange-plus: transparent, and worth the paperwork at volume
Interchange-plus pricing separates underlying card costs from a disclosed provider markup. The structure can make the provider-controlled layer easier to inspect, but only a statement-based model can show whether a specific offer improves the merchant’s total cost.
Tiered: the one to avoid
Tiered pricing groups transactions into provider-defined categories such as qualified, mid-qualified, and non-qualified. Ask for the qualification rules, review where the merchant’s real transactions land, and compare the resulting effective cost rather than the lowest tier alone.
Where the answer flips
There is no universal volume threshold where one model wins. Ticket count, debit and rewards mix, card-present versus card-not-present share, recurring charges, software, hardware, and contract terms can change the answer.
The zero-cost wildcard
Dual-pricing and surcharge programs can change who bears some payment cost, but they also change displayed prices, receipts, customer communication, refunds, staff workflows, and compliance obligations. Verify current provider rules, card-brand requirements, and applicable law before implementation.