Join or leave a multitenant organization in Microsoft 365

Article
10/20/2023

To join a multitenant organization, a global administrator in the owner organization must first add your organization to the multitenant organization. Once they've done that, you can join the multitenant organization. You'll need the tenant ID of the owner organization in order to join.

Once you've joined, you can leave a multitenant organization at any time.

When you join an existing multitenant organization, the following settings are configured in Microsoft Entra ID:

A cross-tenant synchronization configuration is added with the name MTO_Sync_<TenantID>, but no sync jobs are created yet. (If you already have a cross-tenant synchronization configuration, it remains unchanged.)
An organization relationship is added to the cross-tenant access settings based on the multitenant organization templates for cross-tenant access and identity synchronization. (If an organizational relationship already exists, the existing one is used.)
The multitenant organization template for identity synchronization is set to allow users to sync into this tenant.
The multitenant org template for cross-tenant access will be set to automatically redeem user invitations, inbound as well as outbound.

When you leave a multitenant organization, the cross-tenant access settings and cross-tenant synchronization configurations in Microsoft Entra ID aren't affected.

Join an existing multitenant organization

To join an existing multitenant organization in Microsoft 365

Sign in to the Microsoft 365 admin center as a global administrator.
Expand Settings and select Org settings.
On the Organization profile tab, select Multitenant collaboration.
Select Get started.
Select Join an existing multitenant organization.
Enter the tenant ID of the owner organization.
Select the Allow users to sync into this tenant from the other tenants in this multitenant organization and Suppress consent prompts for users from the other tenant when they access apps and resources in my tenant check boxes.
Select Next.
Select Done.

It can take up to four hours for your tenant to be joined to the multitenant organization.

Note

If you encounter an error when joining the multitenant organization, try again after two hours. If the error reoccurs, contact Microsoft support.

The next step after you join the multitenant organization is to synchronize your users with the other tenants. For details, see Synchronize users in multitenant orgs in Microsoft 365.

Leave a multitenant organization

You can leave a multitenant organization as long as your tenant isn't the last owner tenant in the multitenant organization. You can also remove other member tenants.

To remove a tenant from a multitenant organization in Microsoft 365

Sign in to the Microsoft 365 admin center as a global administrator.
Expand Settings and select Org settings.
On the Organization profile tab, select Multitenant collaboration.
Select the check box next to the tenant you want to remove.
Select Remove tenant.
Read the details regarding tenant removal in the side panel, and then select Remove tenant.

Removing a tenant doesn't change any user synchronization configurations or cross-tenant access settings in Microsoft Entra ID. We recommend you review these settings and make any updates needed after the tenant is removed.

Remove synchronized users from other tenants

When you remove a tenant from a multitenant organization, you might want to stop synchronizing users between that tenant and the tenants that remain in the multitenant organization. This can be done by updating the cross-tenant synchronization configuration in Microsoft Entra ID and removing the security groups being synchronized, then restarting the synchronization with zero users.

Cross-tenant synchronization configurations for multitenant organizations that were created in the Microsoft 365 admin center are named MTO_Sync_<TenantID> in Microsoft Entra cross-tenant synchronization.

To remove the cross-synchronized users:

For the tenant that is leaving the multitenant organization, update the synchronization configurations for each remaining tenant in the multitenant organization where you're synchronizing users.
For each tenant that's remaining in the multitenant organization, update the synchronization configuration for the tenant that's leaving.

To remove your users from other tenants in a multitenant organization:

Sign in to the Microsoft Entra admin center as a Global administrator.
Expand Identity, and then expand External Identities.
Select Cross-tenant synchronization.
Select Configurations.
Select the link for the configuration you want to update.
Select Users and groups
Select the check boxes for the security groups that you want to remove, and then select Remove.
Select Overview.
Select Restart provisioning.

Once the users have been removed from the other tenants' directories, you can stop provisioning for the synchronization configurations or delete them.

Stop user sync and automatic invitation redemption

Once you remove a tenant from a multitenant organization, you might want to stop user sync and automatic invitation redemption with the tenants that remain in the multitenant organization.

To prevent user sync and automatic invitation redemption:

For the tenant that is leaving the multitenant organization, update the cross-tenant access settings for each tenant that's remaining in the multitenant organization.
For each tenant that's remaining in the multitenant organization, update the cross-tenant access settings for the tenant that's leaving.

To prevent user sync and automatic invitation redemption:

Sign in to the Microsoft Entra admin center as a Global administrator.
Expand Identity, and then expand External Identities.
Select Cross-tenant access settings.
On the Organizational settings tab, select the link for the Inbound access settings for the tenant you want to update.
1. On the Trust settings tab, clear the Automatically redeem invitations with the tenant <organization> check box.
2. On the Cross-tenant sync tab, clear the Allow users sync into this tenant check box.
3. Select Save.
Select the link for the Outbound access settings for the tenant you want to update.
1. On the Trust settings tab, clear the Automatically redeem invitations with the tenant <organization> check box.
2. Select Save.