Every card transaction an acquirer or ISO processes carries a promise: if the merchant can’t cover a chargeback, refund, or fine, the acquirer will. That liability is why dispute thresholds sit at the center of every risk conversation. It’s the card brands’ way of measuring whether a merchant, and increasingly the acquirer’s entire portfolio, is operating within acceptable limits.
Card-not-present sales, subscription billing, buy now, pay later, and digital wallets have multiplied the ways a transaction can go wrong. At the same time, Visa and Mastercard have moved from policing merchants one at a time to holding the acquirer directly accountable for its portfolio. For acquirers and ISOs, dispute thresholds are no longer just a merchant problem. They are a portfolio, sponsor bank, and profitability problem.
The Dispute Thresholds That Matter
A dispute ratio compares the number of chargebacks (and, in newer programs, reported fraud) to the number of transactions processed. Each card brand measures it differently, and the thresholds are tightening.
Visa: The Visa Acquirer Monitoring Program (VAMP)
In April 2025, Visa retired its separate fraud and dispute programs and replaced them with a single framework. The VAMP ratio combines issuer-reported fraud (TC40s) and disputes (TC15s) and divides them by settled card-not-present transactions. A fraud report counts even if no chargeback is ever filed.
- Merchant Excessive: a VAMP ratio of 1.50% or higher (reduced from 2.20% on April 1, 2026) with at least 1,500 combined fraud and dispute events in the month. Enrolled merchants face per-event fines that can add up quickly.
- Acquirer Above Standard: a portfolio ratio of 0.50% or higher.
- Acquirer Excessive: a portfolio ratio of 0.70% or higher, with the potential for larger fines.
The acquirer’s threshold is less than half the merchant’s. A merchant running at 1.4% is “compliant” by Visa’s merchant standard, yet it is running at twice the acquirer’s Excessive level and pulling the whole portfolio in the wrong direction.
Mastercard: ECP Today, GMAP in 2027
Mastercard’s Excessive Chargeback Program (ECP) currently flags merchants at two levels:
- Excessive Chargeback Merchant (ECM): a chargeback ratio of 1.5% or higher with at least 100 chargebacks in a month.
- High Excessive Chargeback Merchant (HECM): a ratio of 3.0% or higher with at least 300 chargebacks.
Mastercard’s separate Excessive Fraud Merchant (EFM) program targets e-commerce merchants with a fraud chargeback ratio of 0.5% or higher and at least $50,000 in fraud chargebacks.
Beginning April 1, 2027, Mastercard’s revised Global Merchant Audit Program (GMAP) replaces the Acquirer Chargeback Monitoring Program and follows Visa’s lead. It adds new High Dispute and Excessive Dispute categories that combine reported fraud and non-fraud chargebacks, and it measures acquirers directly: 0.50% for a High Dispute Acquirer and 0.70% for an Excessive Dispute Acquirer. The ECM threshold also steps down over time, from 1.5% toward 0.9% by 2031. Monthly assessments escalate the longer a merchant or acquirer stays in the program and can reach six.
American Express and Discover
American Express and Discover generally treat a chargeback ratio near 1% as excessive, with added fees and, in Amex’s case, loss of the inquiry stage before a chargeback is issued.
Card brand rules change regularly and fees vary by region and acquirer agreement, so acquirers and ISOs should confirm current figures with each network and their sponsor bank.
How Elevated Dispute Rates Impact the Merchant’s Business
When a merchant’s dispute ratio climbs, the acquirer’s exposure climbs with it. Card brand fines land on the acquirer first, and a single high-volume merchant can push an entire portfolio over a VAMP or GMAP threshold. The acquirer has no choice but to pass that risk back to the merchant, usually in this order:
- Higher fees. Chargeback fees, card brand assessments, and per-event program fees are passed through to the merchant. Acquirers also reprice the account with a higher discount rate to reflect the added risk.
- Reserves. The acquirer holds back a percentage of each day’s sales, typically 5% to 10% or more, in a rolling reserve, or requires an upfront or capped reserve. That cash stays tied up for months.
- Lower and slower settlement. Beyond reserves, acquirers may delay funding, cap monthly processing volume, or hold settlement pending review. A merchant may be processing the same sales but receiving far less of it, far later.
- Lower approval rates. When acquirers, and issuers, see elevated levels of risk coming from a merchant, their internal fraud models will begin to reduce approval rates on transactions that would have typically settled. No approval equals no risk. This impact can be a silent and costly expense for a merchant.
- Termination. If rates don’t come down, the acquirer will close the account. A merchant terminated for excessive chargebacks or fraud can be placed on Mastercard’s MATCH list for up to five years, making it extremely difficult to find another processor.
Each of these steps is a cost to the merchant, but each is also a cost to the acquirer and ISO in lost volume, residuals, and staff time. The better outcome for everyone is catching the problem before it reaches the threshold.
How Merchants Can Reduce Their Dispute Metrics
Disputes can’t be eliminated, but most can be reduced at the source. Acquirers and ISOs should expect, and help, their merchants to put these practices in place:
- Use pre-dispute alerts. Visa’s Verifi (Order Insight, RDR and CDRN) and Mastercard’s Ethoca alerts let merchants resolve or refund a dispute before it becomes a chargeback. Keep in mind that under VAMP, a refund does not erase a TC40 fraud report that has already been filed.
- Strengthen fraud screening. Require CVV and AVS, use 3-D Secure on higher-risk transactions, and apply velocity checks and BIN or geolocation rules to stop fraud before it’s authorized.
- Write clear billing descriptors. Cardholders who don’t recognize a charge often call it fraud. Use the brand name customers know, plus a customer service phone number or URL.
- Make customer service easy to reach. Publish phone, email, and chat options on the website, receipts, and confirmation emails. A customer who can reach the merchant quickly rarely calls the bank.
- Be transparent about subscriptions, refunds and shipping. Clearly disclose trial terms, rebill dates, and cancellation steps. Send pre-billing reminders and shipping updates so customers aren’t surprised.
- Cancel and refund promptly. Honor cancellation and refund requests immediately. A delayed refund is one of the most common triggers for a preventable chargeback.
- Find the root cause. Track disputes by affiliate, campaign, product, landing page, and MID. A single bad traffic source can drive most of a merchant’s disputes, and shutting it off can do more than every other tactic combined.
- Fight the disputes worth fighting. Submit strong compelling evidence, including Visa Compelling Evidence 3.0 where it applies, to win representments on invalid disputes.
Continuous Underwriting: See the Problem Before the Card Brands Do
Most merchants still learn that they have crossed a threshold from a notice that arrives from their processing partner weeks after month-end. By then, the disputes are counted, the fees are assessed, and the next month’s problem is already underway.
SLYCE360 brings continuous underwriting to the acquirers, ISOs and merchants alike. It acts as a force multiplier for compliance teams, using advanced analytics and automations to monitor chargebacks, TC40 fraud, and dispute trends by connecting directly to a merchants’ CRM, so every dispute can be traced to its affiliate, campaign, or product, and everyone sees the same data so they can fix issues at the source.