What Is Interchange?

Interchange is the base fee that card-issuing banks charge acquiring banks on every card transaction. Visa and Mastercard publish these rates in public schedules, updating them twice yearly in April and October. The fee is expressed as a percentage of the transaction plus a fixed per-item charge, and it flows downstream to the merchant as a non-negotiable cost buried inside the total merchant discount rate.

How Interchange Is Set and Applied

The card networks set interchange rates by category. A merchant never pays interchange directly to the issuing bank. Instead, the merchant's acquirer or payment processor pays it, then marks it up and bills the merchant in aggregate on the monthly statement.

The categories run to hundreds. A few common ones illustrate the structure:

• Visa CPS Retail, swiped debit: 0.80% + $0.15
• Visa CPS Retail, credit, standard: 1.51% + $0.10
• Mastercard Consumer Credit, standard: 1.90% + $0.10
• Visa Corporate Card, electronic: 2.10% + $0.10

These figures are illustrative of published schedules, not results any firm produced.

The category assigned to a transaction depends on data elements the merchant passes at the point of sale. Card-present versus card-not-present, merchant category code (MCC), transaction size, whether AVS and CVV were submitted, and whether the data was settled within required timeframes all shift the rate. A transaction that qualifies for a downgraded interchange category, such as EIRF or standard, can cost the merchant 50 to 150 basis points more than the optimal rate for that card type.

The Flow of Funds

When a customer pays $100 with a credit card, the issuing bank keeps the interchange portion, the acquirer keeps its markup, and the remaining balance settles to the merchant. On a typical small-ticket retail transaction, the merchant might receive $97.00 to $97.50 of the $100. The exact split between interchange and processor markup is usually invisible on the merchant's statement unless the processor provides interchange-plus pricing.

Why Interchange Matters to Audit Recovery Firms

For a merchant fee audit practice, interchange is the largest single cost component in most merchant statements. Processor markups are often 20 to 40 basis points on large-volume accounts. Interchange can run 150 to 300 basis points, sometimes more on corporate or rewards cards. A merchant who negotiates aggressively with its processor but ignores interchange qualification leaves the majority of its card-acceptance cost untouched.

The audit opportunity sits in qualification errors. A merchant may be configured to pass level 2 or level 3 data, which reduces interchange on commercial cards, but its gateway or terminal may drop that data on a subset of transactions. Downgrades accumulate silently. A mid-market merchant processing $8 million annually in card volume can leak $15,000 to $40,000 in excess interchange through qualification failures alone.

The Hidden Complexity

Interchange schedules are public but voluminous. Visa's U.S. interchange reimbursement fees exceed 150 pages. Mastercard's comparable document runs similarly. Most merchants never read them. Many processors summarize interchange into opaque tiers, "qualified," "mid-qualified," and "non-qualified," which obscure the underlying categories. An audit firm that reads the actual schedules and matches them line by line against the merchant's transaction detail can identify where the processor's tier assignment diverges from the network's category assignment.

Where Practitioners Get It Wrong

The most common error is conflating interchange with the total merchant fee. A firm owner quotes a prospect a savings estimate based on the total discount rate, then discovers that 80% of that rate is interchange the processor cannot reduce. The engagement collapses in credibility.

A second error is missing the temporal dimension. Interchange rates change. A rate that was correct in April may be obsolete by November. An audit based on stale schedules produces false findings. Firms that do not subscribe to the networks' official rate publications or rely on third-party summaries without verification date-stamps risk this.

A third error is ignoring the processor's passthrough integrity. Some processors absorb interchange on certain pricing models, then mark up their own rate to compensate. An audit firm that treats every statement as interchange-plus will misread these arrangements. The correct first step is always to confirm the pricing model: interchange-plus, flat rate, tiered, or subscription.

Related Terms in Expense and Audit Recovery

A merchant fee audit practitioner should also understand effective rate, the all-in cost of card acceptance expressed as a single percentage that includes interchange, assessments, and processor markup. Level 2 and Level 3 data refer to the enhanced transaction data required for reduced interchange on commercial card transactions. SaaS license true-up sits in a different cost category but follows a similar audit logic: verifying that the vendor's billed consumption matches the client's actual usage. Duty drawback and sales and use tax reverse audit are sibling recovery practices in the same division, each hunting for overpayments buried in complex regulatory rate structures.

If you run a merchant fee audit practice, the ROI Wire program for merchant fee audit firms uses Email Correspondence, Direct Mail, and Retargeting to reach CFOs and controllers at mid-market merchants who do not know their interchange qualification rate. For more terms in this glossary division, see the expense and audit recovery glossary hub.