Free Tool · Mastercard SMMP
Free Mastercard SMMP Calculator 2026
Check whether your combined refund and chargeback rate could trigger a Mastercard SMMP investigation — and how much buffer you have before the 5% threshold.
Applies from July 24, 2026 · Minimum 500 transactions/month
1Your monthly numbers
Total Mastercard transactions settled this month
Voluntary refunds you initiated (not chargebacks)
Mastercard chargebacks filed against you
SMMP Trigger 3 — combined rate threshold
Your combined refund and chargeback rate is below the 5% SMMP trigger. Continue monitoring monthly — a single bad campaign or affiliate can push you over quickly.
Combined rate
3.50%
2Breakdown
Combined rate
(40 refunds + 30 chargebacks) ÷ 2,000 transactions
SMMP trigger: ≥ 5%
Refund rate
refunds ÷ transactions
Chargeback rate
chargebacks ÷ transactions
Also triggers Mastercard ECM program
Buffer to 5% threshold
combined events you can absorb
Safe margin this month
Also in Mastercard ECM territory
Your chargeback rate alone (1.50%) exceeds the ECM threshold (1.5%). You may be simultaneously facing SMMP investigation risk and MCMP fines — two separate programs with different enforcement mechanisms. Estimate your MCMP fines →
Stay below 5% with proactive dispute management
Keep your combined rate low by fighting chargebacks and preventing refunds. ChargeMate handles dispute responses for $10/case — no integration required.
What is SMMP?
Mastercard's Scam Merchant Monitoring Program — takes full effect July 24, 2026. Unlike ECM, confirmed violations mean immediate processing termination, no fines.
Full SMMP guide →The 4 triggers
Auth rate drops, GRIP letters, new merchant signals, and monitoring provider alerts can all start the 72-hour investigation clock independently.
See all triggers →Mastercard ECM fines
Your chargeback rate (without refunds) is tracked separately under ECM/HECM with a published fine schedule starting at $1,000/month.
ECM fine calculator →What Is the SMMP 5% Combined Rate Threshold?
The Mastercard SMMP (Scam Merchant Monitoring Program) uses a combined refund and chargeback rate as one of four triggers that require acquirers to investigate within 72 hours. When a merchant's combined rate reaches or exceeds 5% of purchase transactions in a rolling 30-day window — with a minimum of 500 transactions — the acquirer is legally obligated to begin investigating.
The formula is straightforward:
The key distinction from other monitoring programs: this includes both voluntary refunds and chargebacks in the numerator. A merchant with a very low chargeback rate (say, 0.5%) but a high refund rate (say, 5%) from a generous return policy would still trigger the threshold. SMMP is designed to catch scam operations that issue rapid refunds to avoid formal chargebacks — but the threshold is broad enough to catch legitimate subscription businesses with high refund rates.
This is why subscription businesses, digital goods merchants, and SaaS companies are disproportionately exposed. Their normal operating patterns — free trial cancellations, billing confusion refunds, and subscription churn — can produce combined rates that look like scam signals to an automated system.
SMMP vs ECM vs VAMP: Which Programs Apply to You
These three programs can apply simultaneously to the same merchant, each measuring something different:
| Program | Network | What it measures | Consequence |
|---|---|---|---|
| SMMP | Mastercard | (Refunds + chargebacks) ÷ transactions ≥ 5% | Immediate termination if confirmed scam |
| ECM / HECM | Mastercard | Chargebacks ÷ transactions ≥ 1.5% | Monthly fines, escalating to $75k/mo |
| VAMP | Visa | (TC40 + TC15) ÷ settled transactions ≥ 1.5% | Monthly fines, account termination risk |
How to Reduce Your Combined Rate
Because the combined rate includes both refunds and chargebacks, you have two levers: prevent chargebacks from being filed, and reduce the conditions that cause customers to request refunds.
Fix your billing descriptor
Unrecognized charges are the #1 cause of "I didn't authorize this" disputes and "what is this charge?" refund requests. Make your descriptor include your brand name and a contact number. Test it yourself — make a charge to your own card and check how it appears in your banking app.
Send receipts and trial-end reminders
A receipt email within 5 minutes of every charge eliminates most billing confusion. A trial-end reminder 3–7 days before conversion prevents customers from discovering the charge on their statement rather than in their inbox. These two automations alone can move the needle more than any other single change.
Make cancellation 3 clicks or fewer
If cancellation is hard, customers dispute instead. Self-service cancellation with immediate email confirmation is non-negotiable. A customer who cancels costs you nothing. A customer who disputes costs you the refund amount plus chargeback fees plus SMMP exposure.
Refund proactively on first contact
If a customer contacts you within 48 hours of an unexpected charge, refund before the dispute clock starts. Yes, refunds count in your combined rate — but a chargeback is worse. It counts in your rate AND your ECM ratio AND your VAMP ratio, plus fees.
Monitor by acquisition channel
Track your combined rate by traffic source. A single affiliate sending high-fraud or high-refund traffic can push your rate above threshold in a single month. Set contractual thresholds and terminate channels that breach them.