ISO vs Acquirer vs Processor vs Gateway
Acquiring · 6 min read · Published · Updated
By Basis Point Payments Advisory
An acquirer holds the merchant agreement and the financial liability, a processor operates the authorization and settlement rails, a gateway orchestrates transactions from the checkout, and an ISO resells and services the relationship without holding the underlying liability.
Four words merchants use interchangeably that describe four different companies with four different incentives — and different power over your account.
| Holds liability | Can approve or close you | Controls routing | Typical incentive | |
|---|---|---|---|---|
| Acquiring bank | Yes | Yes | Partly | Portfolio loss control |
| Processor | No | Influences | Yes | Volume and per-transaction fees |
| Gateway | No | No | Yes, if multi-acquirer capable | Platform stickiness |
| ISO / reseller | No | Influences | No | Margin on the spread |
Why the distinction changes your negotiation
If your counterparty is an ISO, the pricing you are quoted includes their margin on top of the acquirer's, and the risk decisions you are told about are being relayed rather than made. That is not inherently bad — a good ISO earns its spread in underwriting advocacy and service. It matters because when a reserve appears or an account is reviewed, you need to know who is actually deciding, and whether anyone in the chain is representing your position to them.
Questions worth asking before you sign
- Which legal entity is the acquirer on the merchant agreement?
- Who sets and releases the reserve, and under what documented trigger?
- Can this gateway route to a second acquirer without a checkout rebuild?
- Who owns the tokenised card vault, and what is the documented export path?
- What notice period applies to repricing, cap changes and termination?
Frequently asked questions
- What is the difference between an acquirer and a payment processor?
- The acquirer is the bank that holds the merchant agreement and carries the financial liability for the merchant's card transactions. The processor operates the technical rails that authorize, clear and settle those transactions. One company sometimes performs both roles.
- Is a payment gateway the same as a merchant account?
- No. A gateway transmits and orchestrates transactions; a merchant account is the acquiring relationship that settles the funds. A merchant can change gateway while keeping the same MID, or keep the gateway while adding a second acquirer.
Want this reviewed against your own stack?
Basis Point is an independent payments advisory firm. We assess acquiring strategy, underwriting readiness, reserves, disputes and approval-rate performance — see our advisory scope or how an engagement runs. We are not a bank, acquirer, processor or ISO, and we do not guarantee underwriting outcomes.
Discuss Your Payment SetupContinue reading
- How High-Risk Merchant Accounts WorkWhat a MID actually is, who holds the liability behind it, and why two merchant accounts in the same category can behave completely differently.
- Payment Routing StrategyRouting is where redundancy turns into performance — provided the rules are deterministic, measurable and reversible.
- Building a Multi-Acquirer Payments StrategyWhat it takes to run two or more live acquiring relationships without fragmenting reporting, risk or reconciliation.