Interchange and Merchant Discount Rate: How a Card Processing Fee Is Built

A merchant discount rate is three fees in one line: interchange to the card issuer, assessments to the card network and the markup the acquirer keeps. The first two are set by the networks. Only the markup is priced to your file, and on a high-risk MID it is larger because the acquirer prices disputes, fines and termination risk into it. Ask for interchange-plus and negotiate the markup and the fixed fees, not the layers you cannot move.

The merchant discount rate (MDR) is the total fee deducted from each card sale before it settles to your bank account. It is three fees stacked into one line: interchange, paid to the bank that issued the card; network assessments, paid to the card network for the use of its rails; and the acquirer markup, the part the acquirer and its sales channel keep. The first two are set by the networks and, for a given transaction, cost the same whichever acquirer processes it. The third is priced to your file, and on a high-risk MID it is the layer that grows.

The three layers inside a merchant discount rate

The cardholder's bank, the issuer, approves the sale and later receives interchange for it. The card network routes the messages and collects its assessments. The acquirer, the bank that holds your MID, funds your settlement and keeps its markup. Your statement may show them as separate lines, one blended percentage or tiers; the cost underneath is the same.

Interchange: the issuer's share, set by the network

Interchange is the fee the acquirer pays the issuer on each transaction and passes on to you. The card networks publish it in long tables, one rate per combination of card product, transaction environment and merchant category. For a merchant of ordinary size, nobody in the chain negotiates it: not you, not your ISO, not the acquirer. What changes the interchange cost of a sale is the category it qualifies for. Each category has requirements; a transaction that misses them is assigned to a more expensive one, which the industry calls a downgrade. The main variables:

• Card product. Consumer debit, consumer credit, rewards credit and commercial cards each carry their own rate. In the US, debit cards from large issuers carry a regulated interchange cap, so a debit-heavy checkout costs less to process.
• Transaction environment. Card-present sales with a chip read qualify for lower categories than card-not-present sales, and an online store, a subscription rebill or a phone order is card-not-present by definition.
• Merchant category code (MCC). Some MCCs have their own interchange programs. The acquirer assigns the MCC on your MID, and it has to reflect what you sell.
• Data quality and timing. Address verification, the security code, a correct amount at capture and settlement inside the network's window keep a sale in its target category; late settlement or missing data cause a downgrade.
• Recurring indicators. Subscription billing has to be flagged as such in the authorization message, for the category and for the networks' recurring-billing rules.

Network assessments: the fee for using the rails

Assessments, also called scheme fees or network fees, are what the card networks charge for carrying the transaction. The core assessment is a small share of volume; around it sit per-item fees for authorizations and settlements, cross-border and currency conversion fees, and fees for authorization messages that break the network's rules. The fines a network issues under its monitoring programs when a chargeback or fraud ratio crosses a threshold are penalties rather than assessments, but they reach you the same way. None of it is negotiable with the acquirer, which is billed for it and passes the cost through. On an interchange-plus statement these appear as pass-through lines, worth checking against the real network fees; on tiered or flat pricing they sit inside the rate.

The acquirer markup: the only layer priced to you

The markup is what remains of your discount rate after interchange and assessments are paid out. It is quoted as basis points on volume plus a fixed amount per transaction, and it is where the acquirer earns its revenue and pays its costs:

• Underwriting and monitoring. Reviewing the file, the website, the signer and the processing history, then watching the account for as long as it stays open.
• Funding and settlement. The acquirer funds your settlements and carries the loss when a dispute lands after you were paid and cannot be recovered from you.
• Dispute handling. Retrievals, chargebacks and representments are processed by people and systems the acquirer pays for; the per-dispute fee covers part of that, the markup the rest.
• Reserve administration. Holding, releasing and reconciling a reserve, and absorbing whatever it does not cover when an account is terminated.
• The sales channel. An ISO or agent who brings you an account is typically paid a residual out of the markup for as long as the account processes; one acquirer can therefore price the same file differently through two channels.

Interchange-plus, tiered and flat pricing in plain words

Interchange-plus shows the three layers. The markup is written in the agreement as a number, the pass-through fees are itemized, and a change in cost can be traced to its layer. Tiered pricing hides the layers: the acquirer sorts each transaction into a bucket by its own rules, and card-not-present, high-risk volume tends to land in the mid-qualified and non-qualified tiers. Flat pricing is the simplest to read and the hardest to compare. It suits a merchant whose card mix is expensive, rewards and commercial cards with interchange close to the flat rate, and costs the most on a debit-heavy checkout, where the acquirer keeps the spread over regulated debit interchange. Whatever the model, the number that compares offers is the effective rate: total fees for the month divided by total volume. Compute it from the statement, not from the quote.

Why a high-risk MID carries a larger markup

Take a low-risk merchant and a high-risk one selling online to the same cardholder with the same card, coded so that both sales qualify for the same interchange category. Interchange is the same. Assessments are the same. The difference sits entirely in the markup and the surrounding fee schedule, which the acquirer sets on what it expects the account to cost it.

• Dispute exposure. More chargebacks per thousand sales means more handling, more representments and more losses the acquirer absorbs when the merchant cannot cover them.
• Network fines. A merchant that enters a monitoring program generates fines that the network bills to the acquirer first; the markup prices that probability in advance.
• Termination and MATCH risk. High-risk accounts are terminated more often, and every termination leaves the acquirer holding disputes on settled sales, with only the reserve to cover them.
• Fewer acquirers competing. Many acquirers do not underwrite the vertical at all, so there is less pressure on the markup.
• The file itself. A thin file is priced conservatively: no processing history, a signer the acquirer cannot reach, an entity whose state, address and bank do not match. The underwriter has nothing to price against except the vertical's worst case.

That last point is the one a merchant controls. Interchange and assessments do not move; the markup moves on evidence. Processing history, a chargeback ratio inside the thresholds, a visible refund policy, a clear descriptor and a coherent entity file give the underwriter something better than the vertical's average. The entity file is where the director enters the pricing: an IBO (Independent Business Operator) is the US-resident director on the entity behind the MID, and the underwriter pulls that person's credit file, checks the state on the articles against the ID and may call the director at any point in the life of the account. In an IBOCore package the director has no criminal record and a credit score of 650 or more, the entity is incorporated in the director's home state, and the director takes the verification calls for as long as the package is active. None of that changes the interchange table; it changes what the underwriter can see.

What a merchant can and cannot negotiate

Questions merchants ask

Is the merchant discount rate the same as the interchange rate?

No. Interchange is the component paid to the card issuer. The discount rate is interchange plus network assessments plus the acquirer markup. Two merchants can have identical interchange and very different discount rates, because the markup is set on each file. When a quote is described as an interchange rate, ask what sits on top of it.

Does an IBO package change my processing rate?

It does not change interchange or assessments; the networks set those. What it changes is the file the acquirer underwrites: a US LLC or C-Corp incorporated in the director's home state with an EIN, a reachable US-resident director with a clean record and a credit score of 650 or more, a business bank account with full access, and the complete documentation. The acquirer still sets the markup, the reserve and the fees on that file. The IBO package costs $999 setup, then $2,999 per month from 30 days after delivery, whatever the vertical or the billing model.

Should a high-risk merchant always ask for interchange-plus?

Ask for it. Interchange-plus shows the three layers and makes the markup a single number you can compare across offers. Some high-risk acquirers quote only a blended rate and will not itemize; that alone is not a reason to walk away, but you then have to compute the effective rate from the first statements. Whatever the model, the acquirer can change the rate: read the review clause, the notice period and the fees that apply if you leave. A professional who reviews merchant agreements can tell you what a clause means in your situation.

High-risk MID metrics acquirers watch

Once live, your chargeback ratio (CB ratio) is chargebacks divided by transactions; Visa VDMP and Mastercard ECP programs trigger when you breach network thresholds. Rolling reserves (often 10% for 180 days) protect the acquirer against future disputes. MATCH (Terminated Merchant File) is the industry blacklist after a forced termination. MCC (Merchant Category Code) must reflect your real vertical; miscoding is a scheme violation.

• Representment: fighting a chargeback with delivery proof and logs.
• RDR / Ethoca alerts: pre-chargeback refund tools that protect your CB ratio.
• Statement descriptor: keep it recognizable to cut "friendly fraud" disputes.
• Processing cap: volume limit until the acquirer trusts your history.

MID stacking without structure

Spreading volume across many MIDs without separate entities looks like ratio gaming or transaction laundering to risk teams. The durable pattern is one IBO package per MID, clean descriptors, honest MCC, and reserves treated as a cost of doing high-risk volume.

FAQ: quick answers

How fast can I get an IBO package on IBOCore?

Available inventory ships the same day after payment. You receive Articles, EIN letter, registered agent details, bank onboarding pack and signer contact through your merchant dashboard. Processor onboarding typically follows over the next one to two weeks.

Where can I look up payment-processing jargon?

Use the Resources glossary on IBOCore (/resources) for 580+ definitions: MID, chargeback ratio, MATCH, rolling reserve, MCC, RDR, KYB and high-risk vertical vocabulary.