VAMP Was Written for the Merchants It Hits Hardest

Visa's monitoring threshold reads as uniform but behaves as a step function.

VAMP, Visa's Acquirer Monitoring Program, looks uniform from a distance: one ratio, one threshold, applied to every card-not-present merchant that crosses the 1,500-events-a-month minimum. Up close the uniformity is only in form. The regime applies harder to merchants growing into it than to stable ones already inside, and the asymmetry sits in the entry threshold itself.

A merchant doing 1,000 settled CNP transactions a month is invisible to VAMP; their dispute ratio can be 5% and nothing happens. The same merchant at 1,500 transactions is suddenly inside the program, with the same overall practices and the same customers, but an acquirer now reviewing their ratio against a 1.5% Excessive line. Crossing the threshold is a one-way door, and the per-event fee in the Excessive band ($8 per fraud or dispute transaction) compounds faster than the underlying business can adjust.

The count-based denominator makes the trajectory worse. A merchant in a growth phase typically acquires more first-time customers, and first-time customers dispute at higher rates than returning ones. The ratio drifts upward during exactly the period when the absolute event count is also growing fast enough to draw acquirer attention. A merchant at steady state, with the same product and similar margins, looks cleaner on paper. The program runs harder on the merchants it has the most reason to leave alone.