Is the Entra User ID unique per tenant or globally unique?

Harsha Iranna Dalali 0 Reputation points Microsoft Employee
2024-05-29T17:55:26.3866667+00:00

I am looking for clarification on the uniqueness of the Entra User ID for a user : https://learn.microsoft.com/en-us/graph/api/resources/user?view=graph-rest-1.0. Is the ID unique only per tenant or globally unique across all tenants?

Microsoft Security | Microsoft Entra | Microsoft Entra ID
Microsoft Security | Microsoft Entra | Other
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  1. Q&A Assist
    2024-05-29T17:55:26.4066667+00:00
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    The Entra User ID is unique per tenant. It is not globally unique across all tenants.


    References:

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  2. Marilee Turscak-MSFT 37,206 Reputation points Microsoft Employee Moderator
    2024-05-29T22:17:45.29+00:00

    Hi @Harsha Iranna Dalali ,

    I assume you are referring to the object ID/oid attribute. If this is the case, the oid claim or ObjectId property is immutable and unique, so it will uniquely identify the relevant directory object. When a single user resides in multiple Entra ID tenants, the user will contain a different object ID/oid in each tenant. They are considered as different accounts, even though the users log in to each account with the same credentials. So it is unique to both the tenant and across tenants.

    If you're referring to the email address/User ID used to sign into Microsoft 365 (******@contoso.partner.onmschina.cn), this could exist in multiple tenants.

    If the information helped you, please Accept the answer. This will help us and improve searchability for others in the community who may be researching similar questions. If you have further questions, feel free to reach out to me on Teams and I will try to find the solution or connect you with the right person.

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