MasterCard's 90-Day Rule and 150% Recommendation

90-day Rule

MasterCard acquiring banks must compare daily deposits against the average transaction count and amount for each merchant over a period of at least 90 days, to lessen the effect of normal variances in a merchant's business. For new merchants, MasterCard acquiring banks should compare the average transaction count and amount for other merchants within the same merchant business code (MCC) assigned to the merchant. In the event that suspicious credit or refund transaction activity is identified, if appropriate, the acquiring bank should consider the suspension of transactions pending further investigation.

150% Recommendation

To optimize the effectiveness of fraud analysis staff, merchants that appear in the monitoring reports should exceed the average by 150% or more. However, the amount over the average is at the acquiring bank's discretion.