Use this guide to handle loyalty programs, memberships, benefits, and rewards
within the Universal Commerce Protocol (UCP) checkout flow.

## Overview

Use loyalty to build high-fidelity loyalty experiences within UCP flows. It
ensures existing loyalty members can access their benefits during checkout
sessions. By displaying a user's tier, eligible rewards, and immediately
applicable benefits before they finalize a purchase, you can provide a seamless
experience and reduce friction in the checkout funnel.

Google's loyalty experience builds directly on the standard UCP loyalty data
models. See the
[UCP Loyalty Key Concepts](https://ucp.dev/2026-04-08/specification/loyalty/#key-concepts)
guide for detailed explanations of core entities, relationships, and lifecycle
states.

### Benefits of loyalty

Loyalty supports the following core use cases for known program members:

- **Price-impacting benefits:** apply real-time member-only discounts and free shipping offers, and clearly attribute the source of the savings.
- **Non-price benefits:** transparently display the rewards earned from the current transaction or the rewards applicable to future purchases.
- **Status recognition:** verify and display the user's specific loyalty tier and status achievements within your program.

Additionally, for merchants, loyalty improves user retention and conversion
rates by surfacing personalized loyalty benefits and reassuring users that their
member status is recognized on Google's agentic surfaces.

## Prerequisites

To use loyalty, ensure your integration meets the following requirements:

- You must implement [identity
  linking](https://developers.google.com/merchant/ucp/guides/overview/identity-linking). Google experiences only support **verified loyalty** tiers and benefits. Provisional loyalty claims are not supported.
- Publish your UCP profile at `/.well-known/ucp` and include the `dev.ucp.common.loyalty` capability extending the applicable core shopping capabilities. Google only supports loyalty on checkout.
- Enable [discounts](https://developers.google.com/merchant/ucp/guides/overview/promo-codes). While loyalty handles membership state and reward earning forecasts, discounts are required to specify the monetary effect of any applicable price-impacting loyalty benefits (such as member-only pricing or free shipping).

> [!NOTE]
> **Note:** Google surfaces support loyalty integration only at **checkout** for **verified, account-linked** users. Personalized search results are planned for a future release.

## Error handling and user feedback

Loyalty benefits apply only when a user has an eligible membership. To represent these memberships in your integration, use reverse-domain identifiers as map keys.

You must handle loyalty using identity linking:

- **Identity linking:** once a user is authenticated through [identity
  linking](https://developers.google.com/merchant/ucp/guides/overview/identity-linking), securely determine their membership from their identity and populate the `loyalty` data. Use the reverse-domain identifier that corresponds to their membership.

For a complete list of standard error codes and instructions on returning recoverable messages, see [Error codes](https://developers.google.com/merchant/ucp/guides/overview/error-codes).

## Next steps

View the API payloads and technical implementation details for your UCP version:

- [Version 2026-04-08 Loyalty](https://developers.google.com/merchant/ucp/implementation/2026-04-08/loyalty)