Agent Payments Protocol (AP2): What It Is in 2026

The Agent Payments Protocol (AP2) is an open protocol launched by Google in September 2025 that defines how AI agents can authorize and execute payments on behalf of consumers, with cryptographic guarantees about scope, intent, and authority.

AP2 was announced alongside the broader push toward agentic commerce and was designed to be the payments-layer companion to UCP (Google's commerce-journey protocol) and to interoperate with ACP (Stripe and OpenAI's checkout protocol). Where UCP defines how the agent and merchant talk, AP2 defines how the agent and the payment network talk.

The core abstraction is a Mandate: a digitally signed statement from the consumer that defines exactly what the agent is allowed to spend, on what, with what limits, and for how long. The Mandate travels with the transaction so payment networks and merchants can verify the agent had real authorization, not just possession of credentials.

By Q1 2026, AP2 had over 60 partner organizations, including Adyen and Worldpay endorsing the standard, with commercial pilots running on payment networks (Google + payment partner announcements, late 2025 to early 2026).

AP2 introduces three core flows:

1. Mandate creation. The consumer signs a Mandate that specifies the agent's authorization scope: amount limits, merchant categories, time window, single-use vs recurring, and any other constraints. The Mandate is digitally signed and tied to the consumer's payment credentials but does not expose them to the agent itself.

2. Agent transaction initiation. When the agent is ready to pay (e.g. after the consumer has selected a product through a UCP or ACP flow), it presents the Mandate alongside the transaction request. The merchant and payment processor can verify the Mandate cryptographically.

3. Payment network verification. The payment network checks that the requested transaction matches the Mandate's scope (within amount limits, allowed merchant category, valid time window) before authorizing. If anything is out of scope, the transaction is denied at the network level.

This design solves a foundational trust problem in agentic commerce: how does a merchant or network know that the agent is acting with the consumer's real authorization, not just a stolen credential or a runaway prompt? AP2 makes that authorization auditable and revocable.

Three distinct payment-layer protocols emerged in 2025-2026, each with different scope:

The networks (Visa, Mastercard) implement agent-payment infrastructure on their own rails. AP2 is a higher-level governance layer that any payment network or processor can adopt. Mastercard's CDO confirmed in January 2026 that Mastercard participates in all major protocols (UCP, AP2, A2A, ACP), reflecting the industry's expectation that agentic commerce will be multi-protocol for the foreseeable future.

For a retailer, this means: payment processors and networks handle the AP2 / TAP / Agent Pay layer. The retailer's job is to pick a merchant-of-record path (UCP or ACP) and let the payment side resolve through whichever protocol the consumer's network supports.

Retailers have one essential question about AI agent payments: how do you know the agent had real authority to spend? AP2 answers that question with cryptographic Mandates.

For a retailer, this matters in three concrete ways:

1. Chargeback risk reduction. A signed Mandate is auditable evidence that the consumer authorized the specific transaction scope. Disputes that previously fell into murky "my agent did this" categories now have a clear audit trail.
2. Fraud detection at the network layer. Mismatched Mandate-vs-transaction patterns get caught before they reach the merchant. Retailers do not have to build agent-fraud detection in-house; the payment network does it as part of standard authorization.
3. Higher-value transactions safe to automate. Without strong authorization, retailers and networks cap agent transactions at low amounts. Mandates make it possible to extend agent purchasing to recurring orders, replenishment, and high-cart subscriptions without losing dispute defense.

The practical retailer move is: pick a merchant-of-record path (UCP or ACP), make sure your processor supports AP2, and let the payment-network layer handle agent verification.