Move people, data and devices from one Microsoft 365 tenant to another.

Mergers, acquisitions, divestitures and rebrands all end with people who need to work in a different Microsoft 365 tenant. We move their identities, mailboxes, OneDrive, SharePoint sites, Teams and devices in planned waves, keep the two organizations working together while the move runs, and switch the domain over on a planned cut-over weekend.

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What we cover

When it happensMergers, acquisitions, divestitures and rebrands
What movesIdentities, mail, files, Teams and devices
ApproachDiscover, prepare the target, copy, cut over
Coexistence and cut-overWorking together until the cut-over weekend
RisksRisks, and how each is handled
What you getOne tenant, and nothing left behind

When it happens

Mergers, acquisitions, divestitures and rebrands

An acquired company moves into the buyer's tenant. A business unit that is sold leaves for a tenant of its own. Two organizations merge and choose one tenant to keep. A rebrand brings a new name and a new domain. The work is similar each time, but the deadline is rarely ours to choose: a closing date or a separation agreement usually sets it, so the plan works back from that date.

What moves

Identities, mail, files, Teams and devices

Users and groups are created in the target tenant's Entra ID first, with licences assigned, so the data has somewhere to land. Mailboxes, calendars and contacts move next, then OneDrive files and SharePoint sites with their permissions, then Teams with their channels and files. Laptops and phones are enrolled in the target tenant's device management, so policies and apps follow the user.

Some things do not move cleanly, such as Teams chat history and sharing links sent to people outside the company. The plan says, for each one, what will happen to it.

What we do

Users, groups and licences in Entra ID
Mailboxes, calendars and contacts
OneDrive, SharePoint sites and Teams
Laptops and phones enrolled in the target tenant

Approach

Discover, prepare the target, copy, cut over

Discovery maps both tenants: users, mailboxes, sites, teams, the apps that sign in with the old tenant, devices and the security settings on each side. The target is then prepared to a standard before anyone arrives, with identity, conditional access and data protection policies in place. Data is copied in the background while people keep working in the source tenant. A pilot group moves first, and the rest follow in waves or in a single cut-over, whichever the deadline allows.

What we do

Discovery of both tenants
The target tenant prepared to a security baseline
Background copying and a pilot group
Waves, or a single cut-over

Coexistence and cut-over

Working together until the cut-over weekend

Until the move is complete, people in the two tenants still need to email, meet and share files with each other, so we set up guest access and calendar availability between the tenants.

The cut-over itself is usually a weekend. A custom domain can be verified in only one Microsoft 365 tenant at a time, so the domain is removed from the source and added to the target in one planned window. The mail records switch over, a final pass copies what changed since the last sync, and devices move. On Monday people sign in to the new tenant, with help on hand for the first questions.

Risks

Risks, and how each is handled

The domain cannot live in both tenants: everything that depends on it is listed and switched in the same window. Apps that sign in with the old tenant: each one is found in discovery and set up in the target before the cut-over. Broken permissions and sharing links: internal permissions are mapped and re-applied, and the owners of links shared outside are told what will change. Devices that lose their policies: they are enrolled in planned batches, with instructions. Licence gaps: licences in the target are assigned before any data is copied.

What you get

One tenant, and nothing left behind

Afterwards the source tenant can be closed or handed back, once everyone has confirmed nothing is left in it. Our Microsoft partner page sets out the rest of our Microsoft 365 work, from SharePoint and Purview to Copilot, and our Microsoft Consulting team can keep administering and securing the combined tenant.

What we do

A plan that works back from your deadline
Identities, mail, files, Teams and devices in the target tenant
Coexistence while the move runs
A cut-over runbook and first-day help

Questions

Common questions

What moves in a tenant-to-tenant migration?

Users and groups, mailboxes with their calendars and contacts, OneDrive, SharePoint sites, Teams with their channels and files, and devices. A few things, such as Teams chat history and links shared outside the company, do not move cleanly, and the plan says what happens to each.

Can we keep our domain name?

Yes, by moving it to the target tenant. A domain can be verified in only one Microsoft 365 tenant at a time, so it moves in the cut-over window, and the plan lists everything that depends on it.

Can people keep working during the migration?

Yes. Data copies in the background while they work in the source tenant, and guest access and shared calendar availability let the two organizations work together until the cut-over.

How long does it take?

It depends on the number of people, the amount of data and the deadline. Discovery gives the timeline, and the plan works back from your closing or separation date.

Is this the same as an email migration?

Email is part of it. A tenant-to-tenant move also takes identities, files, Teams, devices and the domain itself. A move from Google Workspace or from your own Exchange servers is an email migration, which has its own page.

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