Azure Active Directory B2C: Enable custom attributes in a custom profile policy

In the Add claims and customize user input using custom policies article you learn how to use built-in user profile attributes. In this article, you enable a custom attribute in your Azure Active Directory B2C (Azure AD B2C) directory. Later, you can use the new attribute as a custom claim in user flows or custom policies simultaneously.


In Azure Active Directory B2C, custom policies are designed primarily to address complex scenarios. For most scenarios, we recommend that you use built-in user flows.


Follow the steps in the article Azure Active Directory B2C: Get started with custom policies.

Use custom attributes to collect information about your customers

Your Azure AD B2C directory comes with a built-in set of attributes. However, you often need to create your own attributes to manage your specific scenario, for example when:

  • A customer-facing application needs to persist a LoyaltyId attribute.
  • An identity provider has a unique user identifier, uniqueUserGUID, that must be persisted.
  • A custom user journey needs to persist the state of the user, migrationStatus, for other logic to operate on.

Azure AD B2C allows you to extend the set of attributes stored on each user account. You can also read and write these attributes by using the Microsoft Graph API.

Azure AD B2C extensions app

Extension attributes can only be registered on an application object, even though they might contain data for a user. The extension attribute is attached to the application called b2c-extensions-app. Do not modify this application, as it's used by Azure AD B2C for storing user data. You can find this application under Azure AD B2C, app registrations.

The terms extension property, custom attribute, and custom claim refer to the same thing in the context of this article. The name varies depending on the context, such as application, object, or policy.

Get the application properties

  1. Sign in to the Azure portal.
  2. Select the Directory + subscription filter in the top menu, and then select the directory that contains your Azure AD B2C tenant.
  3. In the left menu, select Azure AD B2C. Or, select All services and search for and select Azure AD B2C.
  4. Select App registrations, and then select All applications.
  5. Select the b2c-extensions-app. Do not modify. Used by AADB2C for storing user data. application.
  6. Copy the following identifiers to your clipboard and save them:
    • Application ID. Example: 11111111-1111-1111-1111-111111111111.
    • Object ID. Example: 22222222-2222-2222-2222-222222222222.

Modify your custom policy

To enable custom attributes in your policy, provide Application ID and Application Object ID in the AAD-Common technical profile metadata. The AAD-Common technical profile is found in the base Azure Active Directory technical profile, and provides support for Azure AD user management. Other Azure AD technical profiles include the AAD-Common to leverage its configuration. Override the AAD-Common technical profile in the extension file.

  1. Open the extensions file of your policy. For example, SocialAndLocalAccounts/TrustFrameworkExtensions.xml.

  2. Find the ClaimsProviders element. Add a new ClaimsProvider to the ClaimsProviders element.

  3. Replace ApplicationObjectId with the Object ID that you previously recorded. Then replace ClientId with the Application ID that you previously recorded in the below snippet.

      <DisplayName>Azure Active Directory</DisplayName>
        <TechnicalProfile Id="AAD-Common">
            <!--Insert b2c-extensions-app application ID here, for example: 11111111-1111-1111-1111-111111111111-->  
            <Item Key="ClientId"></Item>
            <!--Insert b2c-extensions-app application ObjectId here, for example: 22222222-2222-2222-2222-222222222222-->
            <Item Key="ApplicationObjectId"></Item>

Upload your custom policy

  1. Sign in to the Azure portal.
  2. Make sure you're using the directory that contains your Azure AD tenant by selecting the Directory + subscription filter in the top menu and choosing the directory that contains your Azure AD B2C tenant.
  3. Choose All services in the top-left corner of the Azure portal, and then search for and select App registrations.
  4. Select Identity Experience Framework.
  5. Select Upload Custom Policy, and then upload the TrustFrameworkExtensions.xml policy files that you changed.


 The first time the Azure AD technical profile persists the claim to the directory, it checks whether the custom attribute exists. If not, it creates the custom attribute.

Create a custom attribute through Azure portal

The same extension attributes are shared between built-in and custom policies. When you add custom attributes via the portal experience, those attributes are registered by using the b2c-extensions-app that exists in every B2C tenant.

You can create these attributes by using the portal UI before or after you use them in your custom policies. Follow the guidance for how to define custom attributes in Azure Active Directory B2C. When you create an attribute loyaltyId in the portal, you must refer to it as follows:

Name Used in
extension_loyaltyId Custom policy
extension_<b2c-extensions-app-guid>_loyaltyId Microsoft Graph API

The following example demonstrates the use of custom attributes in an Azure AD B2C custom policy claim definition.

    <ClaimType Id="extension_loyaltyId">
      <DisplayName>Loyalty Identification</DisplayName>
      <UserHelpText>Your loyalty number from your membership card</UserHelpText>

The following example demonstrates the use of a custom attribute in Azure AD B2C custom policy in a technical profile, input, output, and persisted claims.

  <InputClaim ClaimTypeReferenceId="extension_loyaltyId"  />
  <PersistedClaim ClaimTypeReferenceId="extension_loyaltyId" />
  <OutputClaim ClaimTypeReferenceId="extension_loyaltyId" />

Use a custom attribute in a policy

Follow the guidance for how to add claims and customize user input using custom policies. This sample uses a built-in claim 'city'. To use a custom attribute, replace 'city' with your own custom attributes.

Next steps

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