The Visa Acquirer Monitoring Program (VAMP) ratio is calculated based on the following formula:
(Monthly # of transactions reported as fraud + # of fraud disputes + non-fraud disputes)
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(Monthly # of settled transactions)
If an acquirer or merchant’s ratio breaches a threshold, Visa places them under the VAMP, and fines apply.
Note: Visa made a significant update to how they will calculate the program ratios, with corresponding increases to the thresholds at which these ratios will result in scheme fees. Read more about these changes here.