The one to know in 2026: most crypto purchases by card land here, and many issuers treat 6051 as a cash advance — instant fees, no grace period, no rewards. Read this MCC before buying bitcoin on a credit card.
The MCC quietly sets the interchange rate, whether the purchase earns rewards, whether it's treated as a cash advance, and how risk models see the merchant. Acquirers assign it at onboarding — and miscoding is a compliance problem, not a shortcut.
Merchant Category Codes are defined under ISO 18245, with network-specific usage on top. Around 500 exist; the ones that come up in real conversations are in our lookup tool.