---
title: cartBuyerIdentityUpdate - Storefront API
description: >-
  Updates the buyer identity on a

  [`Cart`](/docs/api/storefront/2026-10/objects/Cart),

  including contact information, location, and checkout preferences. The buyer's

  country determines [international
  pricing](https://shopify.dev/docs/storefronts/headless/building-with-the-storefront-api/markets/international-pricing)

  and should match their shipping address.


  Use this mutation to associate a logged-in customer via access token, set a

  B2B company location, or configure checkout preferences like delivery method.

  Preferences prefill checkout fields but don't sync back to the cart if

  overwritten at checkout.
api_version: 2026-10
source_url:
  html: >-
    https://shopify.dev/docs/api/storefront/latest/mutations/cartBuyerIdentityUpdate
  md: >-
    https://shopify.dev/docs/api/storefront/latest/mutations/cartBuyerIdentityUpdate.md
api_name: storefront
api_type: graphql
type: mutation
---

# cart​Buyer​Identity​Update

mutation

Updates the buyer identity on a [`Cart`](https://shopify.dev/docs/api/storefront/2026-10/objects/Cart), including contact information, location, and checkout preferences. The buyer's country determines [international pricing](https://shopify.dev/docs/storefronts/headless/building-with-the-storefront-api/markets/international-pricing) and should match their shipping address.

Use this mutation to associate a logged-in customer via access token, set a B2B company location, or configure checkout preferences like delivery method. Preferences prefill checkout fields but don't sync back to the cart if overwritten at checkout.

## Arguments

* buyer​Identity

  [Cart​Buyer​Identity​Input!](https://shopify.dev/docs/api/storefront/latest/input-objects/CartBuyerIdentityInput)

  required

  The customer associated with the cart. Used to determine [international pricing](https://shopify.dev/custom-storefronts/internationalization/international-pricing). Buyer identity should match the customer's shipping address.

* cart​Id

  [ID!](https://shopify.dev/docs/api/storefront/latest/scalars/ID)

  required

  The ID of the cart.

***

## Cart​Buyer​Identity​Update​Payload returns

* cart

  [Cart](https://shopify.dev/docs/api/storefront/latest/objects/Cart)

  The updated cart.

* user​Errors

  [\[Cart​User​Error!\]!](https://shopify.dev/docs/api/storefront/latest/objects/CartUserError)

  non-null

  The list of errors that occurred from executing the mutation.

* warnings

  [\[Cart​Warning!\]!](https://shopify.dev/docs/api/storefront/latest/objects/CartWarning)

  non-null

  A list of warnings that occurred during the mutation.

***

## Examples

* ### cartBuyerIdentityUpdate reference