The short answer
The merchant discount rate (MDR) is the percentage of each card transaction that the merchant pays in fees. The name comes from the original bank accounting treatment — the acquirer would credit the merchant's account for the sale amount less a discount, and that discount was the fee. "2.5% MDR" means you get $97.50 for a $100 sale; the other $2.50 flows to interchange, assessments, and your processor's margin.
Why the name still matters
US processors mostly use modern terminology ("effective rate," "discount rate," "qualified rate") in their marketing. But "MDR" is still the term of art in:
- Most international payment regulations (the EU, UK, India, Australia, Brazil all regulate MDR caps).
- Long-form merchant agreements and card-brand operating regulations.
- Bank financial filings and annual reports.
- Interchange regulation debates (e.g., the Durbin Amendment argued debit MDR caps, not "debit interchange caps").
- Acquirer scorecards and internal margin reporting.
If you're reading a processing contract that talks about "MDR" and you see the modern term "effective rate" everywhere else, they're referring to the same concept.
What operators need to know
- MDR is an all-in blended number. When a contract quotes "2.5% MDR," that usually includes interchange, assessments, AND processor markup. Unlike "rate over interchange," which quotes just the markup. Always clarify which you're being offered.
- MDR applies to volume, not transactions. If your contract says "2.5% MDR on gross sales volume," refunds and chargebacks don't reduce the MDR billing base on most processors. You pay MDR on the original sale, then pay refund/chargeback fees on top.
- International MDR is regulated. If you're selling to EU cardholders through a European acquirer, the EU caps consumer-debit MDR at 0.2% and consumer-credit MDR at 0.3% on cross-border interchange. US acquirers typically pass some of this savings through to you; ask if yours does.
- MDR is what's printed on your statement. When your accountant asks "what's your credit card fee rate," they usually mean MDR. Make sure your answer includes all hidden line items — see effective rate — true cost for the full stack.
How MDR stacks up
Typical US MDR by channel:
- Low-risk retail (grocery, apparel, electronics): 2.0-2.5% blended MDR.
- Low-risk e-commerce (SaaS, apparel DTC): 2.5-2.9% blended MDR.
- Moderate-risk (nootropics, coaching, DTC supplements): 2.9-3.5%.
- High-risk (peptides, CBD, kratom, adult): 3.5-5.5% — with a reserve on top.
Why multi-brand operators care
When we talk about consolidating your brands onto a single parent merchant account, the savings we quote are almost always expressed as MDR deltas. A 60 bps reduction in blended MDR on $1M/mo in portfolio volume is $72,000/yr — typically an order of magnitude larger than the orchestration fee. See our multi-brand savings calculator and interchange-plus.