The headline rate isn't the real rate
Every processor advertises a number. What actually lands on a statement depends entirely on which pricing model sits underneath that number — interchange-plus or flat-rate — and the two behave completely differently once real volume and real card mix show up.
Flat-rate: simple, and priced for simplicity
A flat-rate processor charges one number regardless of card type. It's easy to explain and easy to sell, which is exactly why so many bars, salons, and lower-volume operators get placed on it. The tradeoff: the flat rate is priced to cover the processor's worst-case card mix, which means on cheaper-to-process debit and basic rewards cards, the business is quietly overpaying to subsidize the simplicity.
Interchange-plus: variable, and priced for actual volume
Interchange-plus passes through the actual interchange cost set by the card networks, plus a fixed markup. It takes more explaining and the statement looks more complex, but at real restaurant, nightclub, or banquet-hall volume, it almost always nets out cheaper — because the business is paying the true cost of each transaction instead of a blended average built to protect the processor.
Where the crossover point sits
Roughly speaking, once monthly volume moves past the range where a business is processing daily rather than occasionally, interchange-plus starts winning. Below that, the simplicity of flat-rate can be worth the premium. The only way to know for certain is to look at 2-3 months of actual statements against both models side by side.
What to actually check on a statement
Look for the effective rate — total fees divided by total volume — not the advertised rate. A statement that shows one blended number with no interchange breakdown is a flat-rate statement even if it isn't labeled that way. If the vertical's average ticket and card mix aren't reflected anywhere on the statement, that's a sign the processor isn't pricing for the actual business.