A merchant category code, or MCC, is a four digit code the acquirer assigns to classify what a merchant sells. The card networks maintain the code list and use it to set interchange rates, apply monitoring programs and require registration for certain categories, such as 5967 for direct marketing of digital content or 7995 for gambling.
Why it matters
Your MCC decides whether you owe specialty registration fees, which monitoring thresholds apply to you and how issuers score your transactions. Some merchants are tempted to seek a friendlier code. Deliberate miscoding is transaction laundering in the networks’ eyes: when it is found, the result is fines for the acquirer, immediate termination for the merchant and a likely MATCH list entry. The right move is the opposite: confirm your code is accurate, budget for the fees it carries and let your history under the correct code become your negotiating asset.