An Independent Sales Organization (ISO) sells, boards, and services merchant accounts as an agent of an acquiring bank, the sponsor behind the merchant ID. Visa's public acceptance-entities guide is blunt: ISOs operate as agents on behalf of acquirers, so when sellers sign services contracts with an ISO they are signing with the acquirer (Visa, Beyond the Acquirer, 15 Feb 2024). The ISO is not Visa or Mastercard. It is not the issuing bank that approved the customer's card. In that Visa classification it does not process the sale or receive settlement. Markup is the layer it lives on.
That sales layer exists because card acquiring is a high-volume, low-margin business banks often do not staff with their own sales force. The OCC's Merchant Processing handbook notes that large and midsize acquiring banks commonly use independent sales organizations or membership service providers (ISO/MSP), and that the ISO/MSP solicits merchants and can handle applications, customer service, terminals, charge-backs, and related work for the acquirer (OCC, August 2014). Cards were 79 percent of U.S. noncash payments by number in 2024 (Federal Reserve FRPS, released 1 Jul 2026). Someone has to originate those merchant accounts. The ISO is usually that someone.
Visa, Mastercard, Discover, American Express. They set interchange, assessments, and brand rules. The ISO is not this layer.
The network member that sponsors the merchant ID and is liable to the brands. The ISO is registered under this bank.
The engine that authorizes, captures, and settles. Sometimes the same brand as the ISO, often not.
Sells, boards, and services the merchant account as an agent of the acquirer. Paid from markup, not interchange.
The ISO is a layer, not a synonym for "processor"
Everyday speech calls anyone who "does merchant accounts" a processor. The payments ecosystem is a stack. Name the jobs.
Networks write brand rules and interchange schedules. You almost never contract with them.
The acquirer (sponsor bank) is the bank-side network member. It sponsors the merchant ID (MID), is the party the brands can hold liable, and receives settlement so it can fund you. Only financial institutions can be members of the bank card associations (OCC, August 2014). That is why an ISO needs a sponsor.
The processor authorizes, captures, and settles. It talks to the networks.
The ISO originates and supports the account in front of that bank. Visa lists the typical ISO jobs as solicitation, sales, customer service, seller training, and selling POS or other acceptance hardware (Visa, 15 Feb 2024). The OCC's list is broader: applications, charge-backs, fraud detection, servicing, accounting, terminals, and sometimes transaction processing itself (OCC, August 2014). The difference is the hat. Visa says that if an ISO processes transactions, receives settlement, or sits in the cardholder-data or processing environment, it is classified as a third-party servicer, not as an ISO in that narrow sense (Visa, 15 Feb 2024). One company can wear more than one registered hat. Ask which jobs it actually does on your file.
An ISV is software: POS, invoicing, scheduling, checkout. Software can sit in front of any processor. It is not the ISO unless the same firm is also registered to sell acquiring.
Because third-party organizations are not association members, the acquirer must register them with the card brand before using their services, and the acquiring bank remains liable to the brand for the third party's acts (OCC, August 2014; Visa, 15 Feb 2024). Registration is the acquirer's filing. You still want the registered name in writing.
ISO vs payment facilitator
An ISO is not a payment facilitator. The full contrast is merchant account vs payment facilitator. The short version is whose name is on the MID, and who can receive settlement.
Visa's payment-facilitator model (21 Feb 2024) defines a PF as a third-party agent that can (i) sign a merchant acceptance contract with a sponsored merchant on behalf of an acquirer, and (ii) receive and distribute settlement from that acquirer. Performing either job makes the entity a PF under that definition. Sponsored merchants sit under a master account. Boarding is usually faster. The cardholder descriptor often prints as PF* plus your DBA.
Visa's ISO write-up is the opposite shape: ISOs do not process transactions, do not receive settlement funds, and do not get access to the seller's customer data or the processing environment (Visa, 15 Feb 2024). You get a merchant account sponsored in your name. When you sign with the ISO, you are signing with the acquirer.
If the "ISO" on the quote is taking settlement or signing you as merchant of record, ask which registration it holds. Labels in a sales deck are not classifications.
What you pay, and what the ISO keeps
Card fees are still three layers, no matter who sold the account. Interchange goes to the issuing bank. Assessments go to the networks. Markup is everything else: processor margin, ISO margin, and monthly extras that are not on a network schedule. Typical processing fees are often described as 1.5 percent to 3.5 percent of the transaction plus a per-item fee (U.S. Chamber of Commerce, "How to Calculate Credit Card Processing Fees"). That range is typical, not a quote and not an ISO's residual.
The ISO is paid from markup. The OCC describes the ISO/MSP fee as the amount the acquiring bank pays the ISO/MSP for services, often a percentage of the volume those merchants bring (OCC, August 2014). That is the residual pool. It is not a slice of interchange.
Illustrative. A shop processing $100,000 a month:
| Item | Amount |
|---|---|
| Card volume | $100,000 |
| Fees at a 2.50% effective rate | $2,500 |
| Interchange and assessments (illustrative) | $2,100 |
| Markup pool | $400 (40 basis points) |
| ISO residual at a 60% split of that pool | $240 |
The $2,500 is what you paid. The $240 is what the sales organization kept, if that is the split and the waterfall. Confirm both on a real statement. A fat split on an inflated buy rate can cost you more and still pay the rep less than a thinner split on true cost-plus. The merchant-facing test is effective rate. The rep-facing test is the waterfall.
Who to name before you sign
Read the merchant agreement for four names, not one logo.
- The registered ISO/MSP, the sales and service organization that boarded you.
- The acquiring bank, the network member that sponsors the MID.
- The processor, the engine that switches the sale.
- Whose name is on the MID. Yours, on a true merchant account. Someone else's master, on a payfac.
Ask what happens to statements, funding, terminals, and support if the salesperson leaves, and if the ISO is sold. Successor language is a contract term, not a brochure line. If you are the person selling these accounts, the durability of that residual (vesting, portability, successor protection) is how ISO residuals work.
A practical rubric, not a bake-off:
- Can they show the registered ISO/MSP name and the sponsor bank on a page you can keep?
- Is pricing one of the six models (interchange-plus, tiered, flat-rate, surcharge, dual pricing, interchange optimization) stated as that model, or a teaser qualified rate?
- Are interchange and assessments passed through, or bundled into a number you cannot audit?
- Who do you call when a batch is missing: the ISO, the processor, or the bank?
- If you leave, do you take the MID history, or start underwriting over?
Quality of third-party service varies widely. The OCC tells banks to run real due diligence on ISO/MSP principals, finances, and registration, and to keep the bank liable even when work is outsourced (OCC, August 2014). You are not the examiner. You can still refuse a quote that cannot name the acquirer.
The ISO is the sales and service layer in front of an acquiring bank. It is how most independent merchant accounts get boarded. It is not the network. Name the sponsor, name the processor, name the MID, and the statement starts to read like a stack instead of a brand.
FAQ
What is an ISO in merchant services? An Independent Sales Organization sells, boards, and services merchant accounts as an agent of an acquiring bank. Visa says that when you sign a services contract with an ISO, you are signing with the acquirer. The ISO is not the card network and, in that classification, does not receive your settlement.
Is an ISO the same as a payment processor? No. The processor is the engine that authorizes, captures, and settles. The ISO is the sales and service layer in front of an acquiring bank. One company can be registered for both jobs. Ask which hat is on your file.
What is the difference between an ISO and a payment facilitator? An ISO originates a merchant account sponsored in your name; signing with the ISO is signing with the acquirer. A payment facilitator seats you as a sponsored merchant under its master account and can receive settlement on your behalf. Whose name is on the MID is the difference.
What does ISO/MSP stand for? ISO is Independent Sales Organization, Visa's term for that sales agent. The OCC writes ISO/MSP, pairing it with membership service provider. Both names mean a third party the acquirer registers with the card brands to solicit and service merchants.
If I signed with an ISO, who is my contract actually with? The acquirer. Visa's 15 Feb 2024 acceptance-entities guide says ISOs operate as agents on behalf of acquirers, so a services contract with the ISO is a contract with the bank-side network member that sponsors the MID.
How does an ISO get paid? From markup, not from interchange or assessments. The OCC describes the ISO/MSP fee as what the acquiring bank pays the ISO for bringing and servicing volume, often a share of that margin. Your bill is still interchange plus assessments plus markup.
Sources
- Visa, "Beyond the Acquirer: Additional Visa Acceptance Entities," 15 Feb 2024
- Visa, "The Visa Payment Facilitator Model," 21 Feb 2024
- OCC, Comptroller's Handbook, Merchant Processing, August 2014
- Federal Reserve Payments Study, National Payment Volumes, Top-Line Data (CY 2015-24), last update 1 Jul 2026
- Federal Reserve, "Federal Reserve issues initial findings from its 2025 triennial payments study," 1 Jul 2026
- U.S. Chamber of Commerce, "How to Calculate Credit Card Processing Fees"
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