What is MDR (merchant discount rate)?
One number on the statement, three companies being paid out of it, and only one of them is the company the shop chose.
The merchant sees one percentage. Three companies are being paid out of it.
Where the percentage goes
A merchant quoted 2 percent does not pay 2 percent to one company. That number is a stack.
The largest slice is interchange, which goes to the bank that issued the customer's card. A smaller slice is the scheme fee, taken by the network for operating the rails. What remains is the acquirer margin, kept by the merchant's provider for the service, the risk, and the support.
The merchant sees one number. Three parties are being paid out of it, and only one of them is the company the merchant actually chose.
Why the rate varies so much
Merchants often assume pricing is arbitrary. It is not. It is priced on risk and on card type.
Premium and rewards cards carry higher interchange, because somebody has to fund the points. Card-not-present transactions cost more than in-person ones, because fraud is easier. Industries with high dispute rates pay more. And a merchant on a single blended rate is being averaged across all of it, which is comfortable but rarely cheapest.
India's unusual decision
In most markets MDR is a commercial matter. In India, MDR on UPI and RuPay debit was set to zero by policy, meaning merchants pay nothing to accept them.
This is one of the most consequential payment decisions of the last decade, and it cuts both ways. Acceptance exploded, because a shopkeeper had no reason to refuse. It also removed the revenue that normally funds a payments business, which is why the Indian ecosystem monetises through lending, distribution and services rather than through the payment itself. The transaction became the customer acquisition channel rather than the product.
A shop advertises free delivery. Somebody is still paying the driver. When the delivery genuinely costs nothing, it is because the shop has decided to make its money on something else entirely.
A country looked at the most reliable revenue line in payments and made it zero. The rest of the industry is still arguing about whether that was brilliant.
Where you meet it
Every card machine, every "cards accepted above 500 only" sign, and every merchant who visibly prefers you scan a code.