Here’s what actually happens when you use your credit card: merchants pay a processing fee to the bank that issued your card (and the networks like Visa or Mastercard). That fee usually ranges from 1.5% to 3.5%, depending on how you pay and where you shop. Square breaks this down clearly. If you spend $100 at a restaurant using chip-and-sign, you’re not just paying for dinner—you’re funding part of the payment infrastructure behind the scenes.
But here’s where it gets personal: those same interchange fees directly affect what kind of rewards you earn. Because issuers like Chase or Capital One make most of their profit from merchant fees—not annual dues—they can afford generous cash-back or travel points programs. So when you rack up miles or get 2x on groceries, remember—you’re benefiting from a system designed around those hidden percentages.
That’s why recent changes matter. In late 2025, a major settlement between banks and retailers pushed interchange rates lower across the board, especially for debit cards. But credit card fees stayed high—because consumers still represent the most profitable segment. As Ben Schlappig noted in his analysis at One Mile at a Time, this shift could reshape reward structures long-term. Issuers may start charging annual fees or tightening redemption terms if margins shrink further.
So how do you avoid being nickel-and-dimed? First, stop treating credit cards as free money machines. If you’re not carrying a balance, you’re essentially paying interest on purchases just to earn points. Second, compare APRs and fees before signing up—some cards bury high late penalties or foreign transaction charges in dense legalese. And finally, use your card only for things you’d buy anyway. Rewards only work when you’re already spending intentionally.
The next time your statement shows a tiny “processing fee” line item? That’s not a mystery—it’s the price of convenience, wrapped in complexity.