Merchant discount rate (MDR)
The merchant discount rate (MDR) is the total percentage fee deducted from each card transaction that a merchant accepts, paid to the merchant's acquiring bank and covering interchange fees, card network assessment fees, and the acquirer's own processing margin.
MDR is the all-in cost of card acceptance from a merchant's perspective. For a merchant processing £100 on a consumer debit card in the UK, an MDR of 0.5% means £0.50 is deducted. The merchant receives £99.50. The acquirer distributes this: a portion goes to the card network as assessment fees, the bulk goes to the card issuer as interchange, and the remainder is the acquirer's margin.
MDR varies by card type, merchant category, and processing channel. E-commerce transactions typically carry higher MDR than in-store transactions, as card-not-present carries greater fraud risk. Premium and corporate cards carry higher MDR than standard consumer cards. High-volume merchants negotiate lower acquirer margins, reducing their effective MDR.
For B2B platforms that are also card issuers, MDR creates an interesting dynamic: the platform pays MDR when it accepts cards for its own purchases while earning interchange when its issued cards are used at merchants.
MDR is a direct operating cost for any business accepting card payments. For low-margin businesses (grocery, fuel, utilities), MDR is a material expense that directly affects profitability. Understanding MDR components enables merchants to negotiate with acquirers and make informed decisions about card acceptance policies.
- Blended MDR obscures the true cost structure; merchants may not understand the interchange component they cannot negotiate
- Premium card MDR is significantly higher and can distort profitability on specific transaction segments
- Cross-border card acceptance carries additional fees beyond standard MDR
- Chargeback fees are additive to MDR
- Chargeback fees can significantly increase the effective cost of specific transactions
A mid-sized e-commerce retailer with €25M annual card revenue at 1.8% blended MDR analyzes its transaction mix. 28% of revenue comes from premium credit cards at 2.4% MDR. Routing preferred customers to alternative payment methods reduces blended MDR to 1.5%, saving €75,000 annually.
Related Concepts
Nium's card issuing infrastructure enables platforms to generate interchange revenue from their issued card programs. Businesses that embed Nium-powered card programs can earn a share of the interchange component of MDR on their cardholders' spending, turning card acceptance from a cost into a revenue opportunity through the issuing model.
Answers you didn't know you needed.
What is the difference between MDR and interchange?
Interchange is the fee paid from the merchant's acquirer to the card issuer, set by the card networks. MDR is the total fee the merchant pays to their acquirer; interchange is a component of MDR alongside network fees and the acquirer's margin.
Can merchants negotiate MDR?
Yes, to a degree. The interchange component is set by the card networks and cannot be negotiated. The acquirer's margin can be negotiated, particularly by higher-volume merchants.
Why do different cards have different MDRs?
Card networks set different interchange rates for different card types. Premium and rewards cards generate higher interchange, which flows through to higher MDR for merchants. Regulated consumer debit cards carry capped, lower interchange.
What is a flat-rate MDR?
Some acquirers offer a single blended rate for all card types rather than a variable rate. This simplifies pricing but can be more expensive for merchants with a high proportion of lower-cost card types.
How does Nium relate to MDR?
Nium is a card issuer, not an acquirer. Nium's card infrastructure earns interchange from merchant acquirers, the issuer-side component of MDR. Platform partners who issue cards through Nium participate in this interchange revenue stream.