5users
Two to three working days
A founder, a few staff and a shared inbox. Cutover on an evening, everyone signed in the next morning.
Tenant to tenant migration
Merge, split or rename tenants with one clean cutover.
A merger, an acquisition, a divestiture, a rebrand or a domain change. We plan and run the move from one Google Workspace to another, or one Microsoft 365 tenant to another, with Google's and Microsoft's own tools, copy everything we can ahead of time, and treat the hour your domain moves as the cutover.
Your current tenantYour new tenantWhat moves, and how
Two platforms, two very different toolkits.
Moving between two tenants of the same platform sounds simple. The vendor tools are not symmetrical, so each half of this route has its own rules.
| What | Google Workspace to Google Workspace | Microsoft 365 to Microsoft 365 |
|---|---|---|
| Google's data import from another Workspace: email with its labels, up to 1,000 source users per import | Cross-tenant mailbox migration: email moved together with contacts, calendar, tasks and notes | |
| Calendars and contacts | Moved separately: user-level calendar transfer and contacts by CSV | Travel with the mailbox |
| Files | Drive sharing, ownership transfer or the Drive API | Cross-tenant OneDrive migration by PowerShell, up to 5 TB or 1 million items per account |
| Approval and setup | A super admin of the source approves the import within 24 hours | An Entra app, an organization relationship, pre-staged mail users and the paid per-user Cross Tenant User Data Migration add-on |
| Larger tenants | Google Workspace Migrate (self-hosted Windows servers, Business Standard and above) or Google's Domain Transfer, which is not self-service | Planned in batches per project |
| The source afterwards | Kept until you close it | Mailbox deleted after the move; OneDrive leaves a redirect behind |
| Groups and shared spaces | Rebuilt in the target from the group inventory | Rebuilt in the target from the group inventory |
Based on Google's and Microsoft's own migration documentation, checked October 2026. Limits change; we confirm them for both tenants during discovery.
What does not survive
The catches on this route, named before we start.
Tenant moves fail on constraints nobody read, not on data. These are the ones that shape the plan.
- Google's import is mail onlyLabels come across, but calendars, contacts and Drive need their own methods. We plan each one instead of finding out after the import.
- A 24-hour approval windowA super admin of the source tenant has to approve Google's import within 24 hours. In an acquisition that person often works for someone else, so we book the moment in advance.
- Source mailboxes are deletedMicrosoft's cross-tenant mailbox move removes the source mailbox afterwards. Anything that must stay with the seller is exported first.
- Holds stop the moveA mailbox on hold cannot be moved across tenants. Legal and retention holds are reviewed with whoever owns them before the batch is built.
- OneDrive moves onceThe cross-tenant OneDrive move has no delta pass. We schedule it close to cutover and freeze edits for that short window.
- Domains must differ during the moveMicrosoft requires different source and target domains for mailbox migration, which is why the domain itself moves at the end.
Plan around the day the domain moves.
Plan for a domain to live in one tenant at a time. Everything that can be copied ahead is copied ahead, and the hour the domain changes tenant becomes the cutover.
Agree the end state
Who moves, who stays, which domain ends up where, which shared files belong to whom, and who on each side approves what.
Inventory both tenants
Users, aliases, groups, shared drives or sites, holds, integrations that send mail, and sizes, with the catches for your half of the route.
Identity in the target
Accounts created on a temporary or secondary domain in the target tenant, groups rebuilt, and for Microsoft 365 the add-on licences, Entra app and organization relationship in place.
Seed while people work
Mail history and files copied in the background, a pilot group first, while everyone keeps working in the source tenant.
Move the domain
In your window: the domain released from the source, added to the target, MX switched, and the target's DKIM and SPF published, with the one-time OneDrive move and a final sync in the same window.
Reconcile and hand off
Message and file counts compared per user on both sides, addresses renamed to the real domain, and a one-page runbook for the admins who inherit the tenant.
Timeline and pricing
How long it takes, and how the price is set.
Typical calendar time from kickoff to reconciled hand-off for mail, calendars and contacts. Large file libraries add seeding time in the background, not downtime.
25users
About one week
Groups, shared mailboxes and a file library come into play. One seeding pass, one evening or weekend cutover.
100users
Two to three weeks
Seeded in waves by department with a pilot group first. The MX change still happens once, in one window.
- One fixed price per migration. Set after the discovery call from the number of users, the sources and the file volume. It changes only if the scope does.
- Licences are yours. You buy Google Workspace or Microsoft 365, and any vendor add-on the route needs, directly. We advise on the tier; we do not resell it.
- Included. Planning, data migration, DNS and email authentication, the cutover window, reconciliation, a sign-in session for your team and thirty days of questions afterwards.
How we scope, quote and invoice is on how we work.
Before you decide
Straight answers.
When is this the right route?
A merger or acquisition that consolidates two companies, a divestiture that splits one off, a rebrand that retires a name, or a domain change easier done in a fresh tenant.
Why does the domain set the date?
Plan for a domain to live in one tenant at a time. Until it leaves the source, the target cannot receive its mail, so the hour it moves is the cutover.
Does Google's import move everything?
No. It moves email with labels for up to 1,000 source users. Calendars, contacts and Drive move separately, and larger tenants use Google Workspace Migrate or Domain Transfer.
What about Microsoft 365 to Microsoft 365?
Mailbox moves need a paid per-user add-on, delete the source mailbox, and are blocked by holds. OneDrive moves once, with no delta pass.
Can people keep working?
Yes. History is copied while everyone works in the source tenant. The interruption is the cutover window plus a short sign-in session.
Changing platform as well?
If the target runs on the other platform, see Google Workspace to Microsoft 365 or Microsoft 365 to Google Workspace.
Product names and logos belong to their respective owners.
Tell us which two tenants become one, or one becomes two.
Thirty minutes, free. Bring the user count on each side, which domain ends up where and your closing date, and you leave with a plan, the known catches and a fixed price.