ISO

What Is an ISO in Payments? Definition and How It Works

Definition

An ISO (Independent Sales Organisation) is a company registered with card schemes to resell acquiring services, signing merchants to payment acceptance agreements on behalf of acquirers in exchange for a revenue share on processing volume.

How it works

The ISO model is the primary distribution channel through which acquirers reach merchants that they would not serve cost-effectively through direct sales. Acquirers have the payment infrastructure and regulatory licences but may lack cost-effective sales channels for small and mid-market merchants. ISOs fill this gap: they have direct merchant relationships, sales organisations, and vertical market expertise.

Visa and Mastercard maintain ISO registries and require ISOs to be registered with the schemes to receive merchant processing revenue. Registration requires compliance with scheme rules, financial vetting, and ongoing compliance obligations.

ISOs may operate in two modes. A reseller ISO introduces merchants to an acquirer and earns a residual revenue share based on the merchant's interchange margin. A processing ISO has deeper integration with the acquirer, may handle some or all of the merchant's customer service and boarding, and earns a larger margin in exchange for more operational responsibility.

The ISO's revenue is the spread between the acquirer's wholesale rate and the rate billed to the merchant. Residual income from large merchant portfolios can be substantial; the ISO model creates long-term recurring revenue streams tied to merchant processing volume.

Why it matters

ISOs extend acquirer reach into SMB and mid-market segments that acquirers cannot profitably serve through direct sales; the ISO provides local market expertise and merchant relationships. ISO income is a residual share of the interchange margin: recurring revenue that scales with merchant portfolio volume and persists as long as merchants remain active. Unlike PayFacs, ISOs do not hold transaction settlement liability; the merchant has a direct acquirer relationship and the acquirer bears primary transaction risk. ISO revenue depends on merchant portfolio retention; merchant attrition erodes residual income; ISOs must deliver value to retain merchants. ISO registration requires ongoing Visa/Mastercard compliance; scheme violations by merchants in the ISO's portfolio can result in fines passed to the ISO by the acquirer.

With PXP

PXP works with registered ISOs and channel partners to extend PXP's acquiring and payment services to merchant segments through ISO distribution relationships. PXP provides ISO partners with processing infrastructure, reporting tools, and support for merchant portfolio management.

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Frequently asked questions

What is the difference between an ISO and a PayFac from a merchant's perspective?

A merchant boarding through an ISO receives a direct merchant account with the acquirer: the merchant has their own Merchant ID (MID) and their own acquiring agreement. The ISO is a sales and service intermediary. A merchant boarding through a PayFac is a sub-merchant under the PayFac's master account with no direct acquirer relationship. ISO onboarding takes longer but provides a direct acquirer relationship and potentially better rates at scale; PayFac onboarding is faster but the merchant is subject to the PayFac's pricing and policies.

How does ISO revenue actually work?

ISO revenue is a residual share of the processing margin. Example: an acquirer prices a merchant at interchange-plus 0.50%, the acquirer's cost basis is interchange-plus 0.20%, and the ISO is entitled to the 0.30% spread. If the merchant processes USD 1 million per month the ISO earns USD 3,000 per month from that merchant. This residual accumulates across the ISO's entire merchant portfolio.

What compliance requirements do ISOs face from Visa and Mastercard?

Registered ISOs must: maintain registration with Visa and Mastercard; comply with scheme operating regulations including PCI DSS requirements; conduct merchant due diligence according to scheme and acquirer requirements; monitor merchant portfolios for excessive chargebacks and prohibited business activities; report material events to the sponsoring acquirer; and participate in scheme audits on request.

Can an ISO also be a technology provider?

Yes. Many ISOs have evolved into technology-enabled payment companies. Value-added reseller ISOs bundle POS hardware, payment software, industry-specific business management tools, and processing services. In some cases the distinction between ISO, PayFac, and payment service provider blurs. The relevant distinction for merchants is the liability model and rate structure not necessarily the entity's registration category.