Every dispute we have traced so far moves money between four parties. Network monitoring programs sit on top of that flow as a measurement layer. They watch the aggregate output of all those individual reversals, convert it into ratios, and pull a lever when a portfolio drifts outside tolerance. This is where the system stops treating disputes as one-off events and starts treating them as a signal about whether an acquirer and its merchants belong on the network at all.
The mechanism matters because the penalty does not land where the dispute started. Visa and Mastercard hold the acquirer accountable, and the acquirer passes the cost and the pressure down to the merchant. Understanding the counting rules tells you where the threshold sits, who gets billed, and how much runway you have before a fine turns into a termination conversation.
Two networks, two counting philosophies
Visa and Mastercard both monitor disputes and fraud, but they count different things, which means a portfolio can be clean on one network and flagged on the other.
Visa: one blended ratio (VAMP)
The Visa Acquirer Monitoring Program (VAMP) consolidated Visa's older fraud and dispute programs into a single ratio. It became effective on April 1, 2025, with an advisory period through September 30, 2025 and enforcement from October 1, 2025. The 1,500-transaction floor applied from June 1, 2025, and tighter thresholds followed on April 1, 2026.
The VAMP ratio is a count, not a dollar figure:
VAMP ratio = (count of fraud reports [TC40] + count of non-fraud disputes [TC15]) / count of settled transactions [TC05]
The blend is the important design choice. Visa folds fraud reports and non-fraud disputes into the same numerator, so you cannot run a clean fraud book while bleeding non-fraud chargebacks and stay under the line. The ratio only applies once a merchant or acquirer reaches 1,500 or more applicable transactions in the period, which keeps low-volume noise out of the program.
As of April 1, 2026, the merchant excessive threshold dropped to 1.5 percent from the prior 2.2 percent across most regions. Visa also runs an acquirer-portfolio view with an "above standard" band and an "excessive" band, plus separate enumeration thresholds aimed at card-testing attacks.
Mastercard: separate chargeback and fraud tracks
Mastercard keeps disputes and fraud in distinct programs, each with its own trigger.
The Excessive Chargeback Merchant (ECM) program uses two conditions that must both hold: a chargeback-to-transaction ratio in the 1.5 percent to 2.99 percent range and at least 100 first-presentment chargebacks in the month. Clear both and you are flagged ECM. The High Excessive Chargeback Merchant (HECM) tier sits above it, triggered at a 3 percent ratio or higher with 300 or more chargebacks.
The Excessive Fraud Merchant (EFM) program runs in parallel and requires meeting all four of its conditions in the same two-month measurement window (the months need not be consecutive): at least 1,000 e-commerce transactions, $50,000 or more in fraud-related chargebacks, a fraud ratio of at least 50 basis points, and 3D Secure used on fewer than 10 percent of e-commerce transactions (under 50 percent in regulated regions). Because all four must hit together, EFM specifically targets merchants who carry real fraud volume and have declined to lean on 3DS to push liability back to issuers.
A worked example
Say an e-commerce merchant on Mastercard runs 60,000 transactions in a month and takes 1,050 chargebacks. The ratio is 1,050 / 60,000, or 1.75 percent. That clears the 1.5 percent floor, and the count clears 100, so the merchant lands in ECM. It does not reach the 3 percent HECM ratio, so it stays in the lower tier for now.
Run the same book through Visa. Suppose the merchant also generated 400 TC40 fraud reports, and dispute and fraud volume is roughly comparable. The VAMP numerator blends fraud plus non-fraud, so even if the non-fraud chargeback rate alone looks survivable, adding the fraud reports can push the blended ratio past the 1.5 percent merchant line. The same underlying performance produces a flag on Visa for a different reason than it does on Mastercard. That divergence is why dispute-ops teams track both ratios separately rather than assuming one number covers both networks.
The fines, and how they escalate
Penalties are structured to start small and compound the longer you stay over the line, which is the network's way of forcing remediation rather than collecting revenue.
Mastercard's ECM schedule escalates by the number of months above threshold. Month one carries no assessment. Months two and three are $1,000 each, months four through six rise to $5,000, months seven through eleven to $25,500, months twelve through eighteen to $50,000, and nineteen months or more reach $100,000 monthly. HECM scales higher, into the low hundreds of thousands per month. Exit requires staying below threshold for three consecutive months.
Visa's enforcement lands on the acquirer for the portfolio, and acquirers in turn assess merchants and may impose remediation plans or offboard accounts that will not come down. The structural point holds across both networks: the merchant feels the penalty, but the network bills the acquirer, so the acquirer has every incentive to act on your account before its own assessment grows.
What pulls a transaction out of the count
The counting rules also define the escape hatches, and these are the levers worth knowing.
On Visa, resolving a dispute before it becomes a formal chargeback keeps it out of the VAMP numerator. Rapid Dispute Resolution refunds eligible transactions automatically under preset rules, and a successful Compelling Evidence 3.0 outcome removes both the dispute and its associated fraud report from the ratio. We cover the evidence mechanics of CE3.0 and pre-dispute resolution in the next module; here the point is narrower. These tools are not just about winning a single case, they directly move your program ratio.
The asymmetry to internalize: once a chargeback is counted, winning the representment recovers the money but does not always remove the chargeback from the monitoring count. Prevention before the count is recorded is worth more to your ratio than a win after it.
Takeaway
Monitoring programs convert the four-party dispute flow into a small set of ratios that decide whether your portfolio is welcome on the network. Track the VAMP blended ratio and Mastercard's separate ECM and EFM triggers as distinct numbers, watch both the percentage and the raw count because each network gates on both, and treat pre-dispute resolution as ratio management rather than case management. The fine schedule gives you months of runway, but it compounds, and the acquirer holding your contract is watching the same clock you are.