Acquirer

The acquirer is the merchant-facing side of the card payment system. Understanding the acquirer’s role — and the commercial relationship it creates — is essential for any merchant or payment operator negotiating processing terms.

The Acquirer’s Role in a Card Transaction

When a customer pays by card, the transaction flows as follows:

1. The merchant’s payment gateway submits an authorization request to the acquirer.
2. The acquirer routes the request through the card network (Visa, Mastercard) to the issuer (the cardholder’s bank).
3. The issuer approves or declines the authorization.
4. The acquirer relays the response to the merchant.
5. At settlement, the acquirer nets the transaction proceeds against the MDR and deposits funds into the merchant’s account.

Acquirer Liability

Acquirers assume meaningful risk in the payment chain:

• Credit risk: If a merchant cannot fulfill chargebacks or reversal requests (e.g., due to insolvency), the acquirer is liable to the card network.
• Fraud risk: Acquirers are responsible for ensuring their merchant portfolios comply with card network fraud thresholds.
• Compliance risk: Acquirers are responsible for ensuring merchant PCI DSS compliance and KYB (Know Your Business) due diligence.

This risk exposure explains why acquirers implement reserve requirements, chargeback thresholds, and merchant category restrictions in their contracts.

Acquirer vs. PSP

A Payment Service Provider (PSP) may act as an acquirer directly (if licensed) or partner with an acquirer. Stripe, for example, is both a PSP and an acquirer in markets where it holds acquiring licenses. Smaller PSPs route through partner acquirers, which adds a layer to the cost structure.

For merchants, working with a PSP that has direct acquiring licenses (rather than one that relies on third-party acquirers) typically means more control over the commercial terms and faster access to settlement data.