Question 1

Can two Microsoft 365 tenants be merged?

Accepted Answer

Yes — data and users from one tenant can be migrated into another. There is no single 'merge button', so the project moves each workload (identity, email, files, Teams) in a planned sequence using supported migration methods.

Question 2

What moves automatically?

Accepted Answer

Very little moves without planning. Supported migration tooling can move mailbox content, OneDrive files, SharePoint content and, with cross-tenant features or third-party tooling, certain other workloads — but each requires identity mapping, licensing and configuration first.

Question 3

What doesn't move?

Accepted Answer

Identities, devices, security configuration, applications, permissions and business processes do not migrate automatically. Conditional Access policies, Intune configuration, app registrations and third-party integrations are typically rebuilt or reconfigured in the target tenant.

Question 4

Can domains be transferred?

Accepted Answer

Yes. A custom domain can be removed from the source tenant and added to the target — but it can only exist in one tenant at a time, so the change must be carefully sequenced around mail flow, sign-in and DNS (including SPF, DKIM and DMARC).

Question 5

Can Teams migrate?

Accepted Answer

Teams structures, files and standard channel content can be migrated with planning; the SharePoint content behind Teams moves through supported migration routes. Some elements — such as certain chat history, apps and tabs — may need third-party tooling, rebuilding or archiving, which discovery identifies.

Microsoft 365 Tenant-to-Tenant Migration

What This Migration Covers

From the Blog