SMMP, Mastercard’s Scam Merchant Monitoring Program, is the network’s mechanism for identifying and cutting off merchants operating scams, enforceable from July 24, 2026. The trigger is a combined refund and chargeback rate above five percent over any rolling 30 day window, with at least 500 transactions; crossing it obliges the acquirer to investigate the merchant within 72 hours.
Why it matters
SMMP works nothing like the fine ladders of the Excessive Chargeback Program: there are no assessments and no remediation tiers. If the investigation concludes the merchant is a scam operation, Mastercard and Maestro acceptance stops immediately, with no grace period and no appeal ladder. Two design choices deserve attention: refunds and chargebacks are counted together, so refunding aggressively to suppress disputes does not lower the SMMP number, and winning a representment does not remove the chargeback from the calculation. Subscription and trial merchants, whose refund plus dispute totals run structurally high, should track the combined rate per rolling window as a standing metric.