NMI is a payment processor that handles credit card transactions for businesses

NMI (Network Merchants Inc.) is a payment gateway and processor that sits between your business, the customer's bank, and the card networks. When a customer enters their card details on your checkout page, NMI encrypts that information, sends it to the card networks and banks for approval, and tells your system whether the transaction went through. NMI does not store the card data on your servers — it handles that part itself, which reduces your fraud risk and compliance burden.

NMI operates as both a gateway (the software layer that processes the transaction) and a processor (the company that actually moves the money). This means you work with one vendor instead of coordinating between separate companies. The money from approved transactions moves into your merchant account, usually within one to three business days.

NMI serves businesses of all sizes, from solo e-commerce sellers to large retail chains. It also works with subscription billing, invoicing, and recurring payments — not just one-time purchases. The company has been operating since 1998 and is owned by Paysafe, a larger payment processing group.

Key Takeaways

  • NMI encrypts card data and routes it to banks and card networks, so sensitive information never sits on your own servers.
  • You receive transaction results in real time and can see approval or decline codes that tell you why a card was rejected.
  • NMI charges a percentage of each transaction plus a per-transaction fee, and rates vary based on your business type and card volume.
  • NMI integrates with shopping carts, invoicing software, and point-of-sale systems through APIs and pre-built plugins.
  • Disputes and chargebacks are handled through NMI's dashboard, where you can upload documentation to contest a customer's claim.

How the transaction flow works from card swipe to settlement

When a customer enters their card number at checkout, NMI's gateway when ready encrypts it and sends it to the card networks (Visa, Mastercard, American Express, Discover). The networks route the request to the customer's bank, which checks the account balance and fraud signals. The bank sends back an approval code or a decline reason — "insufficient funds," "card expired," "suspected fraud," and so on.

NMI displays this result to your customer in seconds. If approved, the transaction is marked as authorized but not yet settled. At the end of each business day, you submit a batch of authorized transactions to NMI for settlement. NMI then moves the money from the customer's bank account through the card networks into your merchant account. This settlement window is why you see funds arrive one to three days after a sale, not when ready.

Throughout this process, NMI logs every step — the timestamp, the amount, the card type, the approval code, and the customer's address. You can view this history in your NMI dashboard and read reports for accounting or dispute purposes.

What fees NMI charges and how they compare

NMI's pricing model includes three main components: an interchange fee (set by the card networks, not NMI), an assessment fee (also set by the networks), and NMI's own markup. The markup is where NMI makes its money and where rates vary most by business type.

For a typical online retail business, NMI charges between 2.2% and 2.9% of each transaction plus $0.25 to $0.30 per transaction. A $100 sale might cost you $2.49 to $3.19 in fees. Subscription billing and recurring payments often have lower rates because they carry less fraud risk. High-risk businesses — like adult content, gambling, or CBD sales — pay higher rates, sometimes 4% or more.

NMI also charges monthly fees for gateway access (usually $20 to $50), PCI compliance scanning (around $100 per year), and optional services like fraud detection or chargeback management. If you process very low volume, some of these monthly fees may not explore. You should request a quote based on your actual business type and expected monthly volume, because published rates are starting points, not fixed prices.

Integration options: APIs, plugins, and hosted pages

NMI offers three main ways to accept payments. The first is a hosted payment page — you send the customer to an NMI-hosted form where they enter their card details. This is the simplest option because you never touch the card data yourself, but it means the customer leaves your website briefly, which can reduce conversion rates.

The second is a direct API integration. You build your own checkout form on your website, and your code sends card data directly to NMI's servers. This requires a developer and more technical setup, but it keeps the customer on your site and gives you full control over the checkout experience. You must follow PCI compliance rules when handling card data this way.

The third is a pre-built plugin for popular platforms. NMI has plugins for WooCommerce, Shopify, Magento, and other shopping carts. You install the plugin, enter your NMI credentials, and the integration is ready. These plugins handle the API calls behind the scenes, so you do not need to write code yourself.

How disputes and chargebacks work through NMI

When a customer disputes a charge with their bank — claiming they did not authorize it, did not receive the goods, or received something different from what was advertised — the bank files a chargeback request with NMI. NMI notifies you through your dashboard and gives you a window (usually 7 to 10 days) to respond with evidence that the transaction was legitimate.

Evidence includes the customer's order confirmation, shipping tracking, delivery signature, email correspondence, or a signed receipt. You upload this documentation through NMI's chargeback management tool. NMI then submits your evidence back to the bank. The bank reviews both sides and decides whether to reverse the chargeback or uphold it.

If you lose a chargeback, the customer's money is returned to them and deducted from your merchant account. You also pay a chargeback fee (usually $15 to $100 per dispute). If chargebacks exceed a certain threshold — typically 1% of your monthly transaction count — NMI may flag your account as high-risk or terminate your processing agreement.

Security and PCI compliance requirements

NMI is PCI DSS Level 1 certified, which is the highest security standard for payment processors. This means NMI's systems are audited annually by third-party security firms and meet strict encryption, access control, and data protection standards. When you use NMI, you inherit some of this protection because the sensitive card data is encrypted before it reaches your servers.

However, you still have compliance responsibilities. If you use a hosted payment page, your compliance burden is minimal — NMI handles most of the security. If you build a custom checkout form using NMI's API, you must follow PCI DSS rules yourself. This means using HTTPS encryption, not storing full card numbers, and passing annual security audits. Many businesses hire a PCI compliance consultant to handle this.

NMI also offers optional fraud detection tools that flag suspicious transactions based on address mismatches, velocity checks (too many transactions from one card in a short time), and other signals. These tools reduce your chargeback risk but are not included in the base service.

When NMI is a good fit and when it is not

NMI works well for e-commerce businesses, subscription services, and invoicing-based models. It is particularly strong if you need recurring billing, because NMI's system is built to handle subscriptions and automatically retry failed payments. It is also a solid choice if you want to avoid being locked into a single platform — NMI integrates with many shopping carts and accounting software, so you can switch platforms later without losing your payment processing.

NMI is less ideal if you need phone support in real time. NMI's support is primarily email and ticketing, with response times of 24 to 48 hours. If you run a high-volume retail operation and need when ready help, you might prefer a processor with live phone support. NMI is also not the cheapest option for very small businesses with minimal transaction volume, because monthly gateway fees can outweigh the savings from lower per-transaction rates.

If your business is considered high-risk — adult content, gambling, CBD, cryptocurrency, or similar — NMI will process you, but at higher rates and with stricter underwriting. You should confirm that NMI accepts your business type before signing up.

Frequently Asked Questions

Does NMI store my customers' credit card numbers?

No. NMI encrypts card data and stores it on its own find servers, not on your website or servers. You never see the full card number after the initial transaction. If you want to store cards for future recurring charges, NMI tokenizes them — it replaces the card number with a unique token that you can use to charge the card again without handling the actual number.

How long does it take to get paid after a customer's card is approved?

Approved transactions are settled in batches at the end of each business day. The money then moves through the card networks and your bank, arriving in your merchant account within one to three business days. Some banks are faster than others, so the exact timing depends on your bank as well as NMI.

What happens if a customer's card is declined?

NMI returns a decline code that tells you why — "insufficient funds," "card expired," "CVV mismatch," "fraud suspected," and so on. You can display a customer-friendly message on your checkout page and offer them a chance to try a different card. NMI does not charge you for declined transactions.

Can I use NMI if I sell internationally?

Yes. NMI processes transactions in multiple currencies and from customers in most countries. However, international transactions carry higher fraud risk and may have higher fees. You should confirm with NMI that your target countries are supported and ask about rates before launching.

What if I want to switch away from NMI later?

You can switch to another processor at any time. NMI does not lock you into a long-term contract (though some integrations may). Your transaction history and customer data stay with NMI, but you can request reports for your records. The main friction is updating your checkout form or plugin to point to the new processor.