How is chargeback ratio measured?
The basic ratio is chargebacks divided by transactions in the same period. Card schemes define their own versions. Since June 2025, Visa’s Acquirer Monitoring Program (VAMP) uses a count of fraud reports plus disputes, divided by settled card-not-present transactions. Visa’s Excessive Merchant threshold is 220 basis points (2.2%) in CEMEA, 150 basis points in Latin America and the Caribbean, and 150 basis points in Asia Pacific, Canada, the EU and the US from 1 April 2026, each with a minimum monthly count. Mastercard’s Excessive Chargeback Program starts at 1.5% and 100 chargebacks in a month. Thresholds change, so the current scheme documents and the acquirer are the reference.
Why does chargeback ratio matter?
Above the thresholds, acquirers face scheme fines, which they pass to merchants, along with higher reserves, extra monitoring or termination. As an illustrative example: 40,000 settled card-not-present transactions with 200 disputes and 150 fraud reports give a VAMP-style ratio of 350 ÷ 40,000, or 87.5 basis points. That is below the merchant thresholds but above the 50 basis point level at which Visa flags an acquirer’s whole portfolio, which is why acquirers watch individual merchants closely.
What drives chargebacks in e-commerce?
Stolen cards, customers disputing purchases they did make, unclear statement descriptors, and slow refunds or deliveries. 3-D Secure, clear descriptors, refunds before disputes, customer verification before large amounts and blocking cards linked to past chargebacks all lower the ratio.
Where does Omno use it?
Omno’s card blocking, customer groups and customer verification levels can restrict which customers reach which PSPs, and transaction-level reporting supports ratio monitoring per PSP and merchant account.