You tap your card, the terminal beeps, and a receipt prints. From where you stand, money just moved from your account to the coffee shop. What actually happened is stranger: nobody moved any money at all in that moment, and at least four separate companies just agreed to owe each other something. Understanding that choreography explains a lot, including why the shop down the street sometimes has a "$5 card minimum" sign taped to the register.
The four parties on a single swipe
The industry calls this the four-party model, and the name is literal. There is the cardholder (you), the merchant (the coffee shop), the issuer (the bank that gave you the card and fronts the money), and the acquirer (the merchant's bank, which collects card payments on the shop's behalf). Sitting in the middle is the card network, Visa or Mastercard, which owns the rails everyone communicates over but does not itself hold anyone's account.
When you tap, the terminal sends the transaction to the acquirer, who routes it across the network to your issuer. The issuer checks that your account is real, has room, and does not look fraudulent, then approves or declines in well under a second. That approval is a promise, not a transfer. The actual money moves later, in batch, during a settlement process where the issuer pays the acquirer and the acquirer credits the merchant, usually a day or two after the beep you heard.
Why split issuing and acquiring into different companies at all? Because it lets banks compete to sign up cardholders and, separately, lets acquirers compete for merchants, while a single shared network keeps everything interoperable. Your regional credit union's card works at a food truck in another state precisely because neither of them has to know the other exists.
Interchange: the fee nobody quotes you
Here is the part that runs the whole economy underneath. On that promise-to-pay, the acquirer pays a fee to the issuer called interchange. It flows from the merchant's side to the bank that issued your card, and the logic is that the issuer is carrying the risk: it extended the credit, it eats the loss if the charge is fraudulent, and it funds the rewards points you are quietly accumulating.
Crucially, the issuer does not set that fee and neither does the merchant negotiate it. The network publishes interchange rates, and they are dizzyingly specific. A basic consumer Visa card at a normal retailer might run about 1.51% plus $0.10, while a premium "World Elite" rewards card at the same store can run 2.60% plus $0.10. If the merchant's terminal fails to send the right data, the transaction can fall back to a "standard" non-qualifying rate around 3.15% plus $0.10. Those rates get revised twice a year, typically each April and October.
Interchange is only one layer. The merchant does not pay it directly; the merchant pays a bundled merchant discount rate to the acquirer, which stacks interchange plus the network's own scheme fees plus the acquirer's markup. For most businesses that all-in rate lands somewhere between roughly 0.3% and 2% of the sale. Interchange is usually the biggest slice, which is exactly why the fat rewards cards cost merchants the most, and why that "$5 minimum" sign exists: on a $2 coffee, a fixed ten-cent-plus-percentage fee is a painful chunk of the sale.
Why this is suddenly a policy fight
For years this was plumbing only payments nerds cared about. Not anymore. Back in 2011, the Durbin Amendment forced debit cards to support at least two unaffiliated networks and capped debit interchange at a base of about 21 cents, and merchants have wanted the same treatment for credit cards ever since.
That is the pitch behind the Credit Card Competition Act, reintroduced in January 2026 by Senators Durbin and Marshall with a House companion. It would require large issuers to enable a second, unaffiliated network on their credit cards so a merchant could route a Visa-branded transaction over a cheaper network, injecting routing competition without a hard price cap. It picked up an unusual booster when President Trump publicly called swipe fees an "out of control ripoff," though the Senate passed a March 2026 housing bill without attaching it. Combined U.S. credit interchange averaged around 2.36% in 2025, so on trillions of dollars of spending, even small shifts are enormous, which is why banks, networks, and retailers are all lobbying hard.
Next time your card beeps, you know the beep is a promise, the settlement comes later, and a fee you never see just decided who profits from your coffee. For the details, the networks actually publish their full interchange tables online, and they are worth a look if you want to see just how many categories a single swipe can fall into.