NMI, Aug 7, 2026
By Alex Burgin, Founder and CEO, Canyon Payments A 17-year payments veteran whose career spans Visa and CyberSource. Canyon Payments is a featured NMI partner. Read NMI's case study on our work across their gateway.
What you'll learn
In a hurry? The first 24 hours
NMI (originally Network Merchants, Inc.) is a payment gateway platform built for ISOs, independent agents, and white-label deployments. If you process payments through NMI, there's a good chance you know it as something else entirely.
It is often a branded gateway carrying your ISO's or reseller's name, powered by NMI underneath. That layer of branding is exactly why chargeback confusion runs deep in the NMI ecosystem.
When a dispute arrives, merchants often aren't sure who sent it, who owns it, or who to respond to.
The NMI gateway is not a party to your dispute. It authorizes and settles transactions. It does not adjudicate chargebacks, and submitting a response into your gateway does nothing to defend your case.
Chargebacks are owned by your acquiring bank, the financial institution that holds your merchant account and settles funds to your business. Depending on your setup, that relationship may run through your ISO, but the acquiring bank must receive your response.
ONE EXCEPTION WORTH KNOWING Some ISOs use NMI's partner-side platform (Merchant Central) to surface dispute alerts and submit responses electronically. If your ISO has given you access to a dispute dashboard, use it.
NOT SURE WHO YOUR ACQUIRING BANK IS? Check the chargeback notification you received. The sender is your acquiring bank, not NMI. Your monthly processing statement also lists your acquirer name, Merchant ID (MID), and dispute contact.
NMI is predominantly deployed through a partner network of ISOs and resellers who build their own branded products on top of the platform. That means your processing relationship usually has more moving parts than a merchant on a direct, single-vendor stack.
Your ISO may help you navigate the process, and your acquirer may accept submissions through a portal your ISO gave you. However, the dispute itself runs between your acquiring bank and the issuer.
WE WORK INSIDE THE NMI PARTNER NETWORK FightMyChargeback is built by Canyon Payments, a payments technology enabler. NMI published a case study on our work across their gateway, including the analytics platform we built on their Query API. We've sat on both sides of this. We know what an ISO can and can't see about your dispute, and we know why the answer to "who do I send this to" is so often unclear. If you're uncertain, start with your ISO or agent.
Once you know who your acquiring bank is, the process follows the same structure for every Visa and Mastercard merchant.
The cardholder claims the transaction was unauthorized or fraudulent, or that goods or services were not delivered as promised.
The charge is reversed, funds are debited from your merchant account, and a chargeback fee is assessed. Fee amounts vary by acquirer and are set in your merchant agreement.
Under Visa's framework, fraud and authorization cases are routed differently than consumer disputes. This affects what your acquirer needs from you and how quickly.
You receive a notification by email or portal containing your MID, the Acquirer Reference Number (ARN), case number, reason code, transaction amount, and deadline.
This is called representment. You submit a rebuttal letter plus supporting evidence through your acquirer's portal or dispute email. They forward it to the network on your behalf.
The cardholder's bank evaluates your response. If it's compelling, the chargeback is reversed and funds are returned. Winning at representment is the goal to avoid further arbitration fees.
Your notification will state a specific deadline. Treat it as the only date that matters.
Visa's framework generally allows 30 calendar days per phase, but that clock belongs to your acquirer. They need time to review your package before their own window closes.
THE DEADLINE ON YOUR NOTIFICATION IS YOUR HARD STOP If you miss it, your acquirer cannot forward your response. Act on the notification the day it arrives. Do not assume you have more time than it states.
Every chargeback response has two components: a rebuttal letter and supporting evidence. Submitting evidence without a letter is a major cause of lost disputes.
The issuer uses these to match your response to the correct dispute file. No match, no review.
Letter header checklist
All of these appear on your chargeback notification. Copy them exactly as they appear, including leading zeros.
The right evidence depends on the reason code in your notification.
| VISA 10.4 Fraud / Unauthorized (Card-Absent) | |
|---|---|
| STRONG | 3D Secure authentication data. If fully authenticated, liability shifted to the issuer. Cite ECI and CAVV values. |
| STRONG | Compelling Evidence 3.0 qualification. Requires two prior undisputed transactions with matching IP or device ID. Can shift liability back. |
| SUPPORTING | AVS and CVV match confirmation. Useful context, but on its own it will not overturn a fraud claim. |
| SUPPORTING | IP geolocation consistent with the cardholder's billing address |
| SUPPORTING | Device fingerprint or prior transaction history on the same device and card |
| VISA 13.2 Cancelled Recurring Transaction | |
|---|---|
| STRONG | Timestamped record of the cardholder agreeing to your recurring billing terms at signup |
| STRONG | History of prior undisputed recurring charges on the same card |
| MODERATE | Pre-billing notification sent before the disputed charge |
| MODERATE | Documentation that no cancellation request exists in your CRM or support logs |
| HARMFUL | Any support record showing a cancellation was requested and not honored. If this exists, refunding is usually the better business decision. |
| VISA 13.1 Merchandise or Services Not Received | |
|---|---|
| STRONG | Carrier tracking confirmation showing delivery to the cardholder's address |
| STRONG | Digital delivery logs: download records, login timestamps, or usage data tied to the cardholder's IP or device |
| MODERATE | Customer communication acknowledging receipt |
| MODERATE | Proof that delivery fell within the window stated at checkout |
| HARMFUL | Delivery to an address different from the one on file, without documented authorization |
| VISA 13.3 Not as Described or Defective | |
|---|---|
| STRONG | Screenshots of the product listing, description, or service agreement showing that what you delivered matched what you advertised |
| STRONG | Communications from the cardholder acknowledging receipt and, ideally, satisfaction |
| MODERATE | Photos or inspection records documenting condition at time of shipment |
| MODERATE | Documentation that you offered a repair, replacement, or refund and the cardholder declined or did not respond |
| WEAK | Your return or refund policy on its own. The issuer is evaluating whether the goods matched the description, not whether the cardholder followed your policy. Policy language alone rarely moves a 13.3. |
Short on time before your deadline? We draft a reason-code-specific representment letter in under five minutes. Start your response
The NMI gateway is not a party to the dispute. Only your acquiring bank can submit your response to the network. This is the single most common NMI-specific mistake.
A letter without the MID, ARN, or case number cannot be matched to the dispute file. No match means no review.
Attaching documents without spelling out what each one shows and how it counters the specific claim. Evidence without context rarely wins.
Assuming you have time you don't have. Treat the date on your notification as a hard stop and respond well before it.
The letter is what gives your evidence meaning. Issuers aren't hunting for reasons to rule in your favor. They check whether your response is compliant and directly addresses the specific claim.
Your letter needs to do three things:
Open with a clear factual assertion. State your position in the first paragraph: "The transaction on [date] for [amount] was authorized by the cardholder and the service was delivered as agreed."
Reference every piece of evidence by name. "Exhibit A is a timestamped login record showing the cardholder accessed their account from IP address [X] on [date]." Vague references get ignored.
Close with an explicit request. Ask the issuer to reverse the chargeback, and confirm you submitted all required materials within the response window.
TONE MATTERS Keep the letter factual and professional. Frustration with the cardholder, emotional language, and accusations all work against you. Issuers evaluate procedural compliance, not feelings.
Building a compliant package takes time. You must structure it for your specific reason code and pull every required identifier. For a merchant doing it the first time, this usually takes hours, not minutes.
FightMyChargeback builds the letter in under five minutes. Enter your transaction details, select your reason code, describe what happened, and upload your evidence. You receive a professionally drafted, issuer-ready letter by email.
No integration with your gateway, ISO, or acquiring bank is required. No contract, no onboarding, no monthly fee. Just the letter.
Reason-code-specific. Issuer-ready. Delivered by email in under five minutes. $15 flat. No contract, no monthly fee.
FOR ISOs AND AGENTS If you support a book of NMI merchants, we offer dispute tooling they can use directly. Talk to us about partner options.
No. The NMI gateway authorizes and settles transactions. It is not a party to your dispute. Chargebacks are owned by your acquiring bank, though some ISOs layer dispute alerting on top.
Your acquiring bank. The fastest way to identify it is to look at who sent your notification. Your processing statement also lists your acquirer and Merchant ID (MID).
Use the deadline printed on your notification. While Visa generally allows 30 days, your acquirer needs time to review and forward your package. Your effective deadline is always earlier.
Your acquirer cannot forward your response and the chargeback stands, regardless of your evidence quality.
Yes. Nothing in the process requires a vendor. Tools like FightMyChargeback exist to compress drafting time, not to unlock system access.
About the author Alex Burgin is the Founder and CEO of Canyon Payments, a Utah-based technology enabler. Alex spent 17 years in payments, including at Visa and CyberSource. He founded Canyon to help merchants cut through payments complexity. Canyon has built CanyonInsights.com, an analytics platform, alongside FightMyChargeback.com and eCheckOnly.com.
FightMyChargeback is a document drafting tool and does not constitute legal advice. Card network dispute rules change periodically; confirm current requirements with your bank.