Tenant-to-Tenant Migration.
Just acquired a company? We merge two Microsoft 365 tenants into one — mail, calendars, contacts, OneDrive, SharePoint, and Teams — while both organisations keep working together throughout, and we hit your deal deadline.
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When Two Become One
The most complex migration there is — handled.
When you acquire a company, two entire Microsoft 365 worlds have to become one. Email, files, sites, Teams, identities, and domains all need to merge — usually against a hard deal deadline and without disrupting either business.
This is the trickiest type of migration, and it's exactly where experience matters. We've untangled overlapping accounts, coexistence, and domain moves before — so your two teams become one without the chaos.
Both companies keep working
The biggest worry in any acquisition is the two teams grinding to a halt. We set up coexistence so both sides email each other and share calendars during the move — then migrate quietly in the background until the day everyone is finally under one roof.
What We Migrate
Every workload, from one tenant to the other.
We bring the acquired company's entire Microsoft 365 environment into yours — completely.
Mailboxes
Every user's full email history and folder structure moves into your tenant's Exchange Online — nothing trimmed, nothing left in the old environment.
Calendars
Personal, shared, and meeting-room calendars all come across — so appointments, bookings, and recurring meetings carry on without a gap.
Contacts
Personal and shared contacts migrate, and the two company directories are merged into one combined global address list everyone can use.
OneDrive Files
Each user's personal OneDrive moves across with its folder structure and sharing intact — their working files follow them seamlessly.
SharePoint Sites
Document libraries, lists, and site content migrate into your tenant with permissions preserved — team knowledge moves over whole.
Teams Channels
Teams, their channels, files, and structure are recreated in your tenant — so collaboration picks up where it left off in the new home.
How We De-Risk the Merge
The hard parts,
handled for you.
Tenant-to-tenant has unique pitfalls. These are the things we get right so your migration doesn't stall.
Coexistence During Transition
Mail flow, free/busy lookups, and a shared directory between both tenants — so the teams work together while we migrate.
Identity Mapping & Dedup
We match users across tenants and resolve duplicate names and accounts cleanly — no two "John Smith" mix-ups.
Permissions Preserved
Sharing and access across OneDrive, SharePoint, and Teams are recreated faithfully in the destination tenant.
Domain Move, Precisely Timed
Moving a domain between tenants is delicate — we plan the timing exactly so addresses switch over without a hitch.
Post-Migration Support
We settle the combined organisation in, reconfigure devices, and support everyone through the first days as one team.
Our Proven Process
Two tenants into one, step by step.
A structured path built around your deal timeline — so the merge lands on schedule and intact.
Discover & Plan
We audit both tenants, map identities and domains, and build a migration plan anchored to your deal close date and business priorities.
Establish Coexistence
We connect the two tenants for mail flow, calendar sharing, and a combined directory — so the organisations can collaborate from day one.
Migrate Workloads
Mail, OneDrive, SharePoint, and Teams move into your tenant in planned waves, validated as we go, while everyone keeps working.
Cutover & Domain Move
We run a final sync, move the domain across, decommission the old tenant, and support the newly combined team as they settle in.
Is This You?
When you need a tenant-to-tenant migration
If your business structure is changing, your Microsoft 365 tenants usually have to change with it. These are the moments we're built for.
You've acquired a company
Bring the acquired team fully into your tenant, branding, and systems.
Two businesses are merging
Combine two equal environments into one unified Microsoft 365 organisation.
You're selling or spinning off a division
Carve out the right users and data into a separate tenant — cleanly and securely.
You're consolidating or rebranding
Merge multiple tenants you've ended up with into a single, well-run environment.
Scenarios We Handle
Every kind of tenant change
Whatever the corporate event behind it, we've planned and run the migration that goes with it.
Acquisition
Merger
Divestiture
Spin-Off
Rebrand
Tenant Consolidation
Carve-Out
We work to your deadline
Deals have close dates — we plan the migration around yours and deliver on it.
We coordinate both IT teams
We liaise with both sides so the move is smooth even when ownership is split.
Why TechSalty?
M&A migrations
without the meltdown.
Just like salt brings out the best in every dish — careful planning brings out the best in a merge.
Microsoft Certified
Microsoft 365 is our specialty — we know tenant-to-tenant migration's pitfalls and how to avoid them.
Coexistence Expertise
Both organisations keep emailing and sharing calendars throughout — no productivity freeze during the merge.
Nothing Lost
Mail, files, sites, and Teams content all come across, validated before the old tenant is retired.
Deadline-Driven
Acquisitions run to a clock. We plan around your close date and deliver the migration on schedule.
FAQ
Tenant-to-Tenant Migration, answered
The questions businesses ask us most when merging Microsoft 365 environments.
Can the two companies still work together during the migration?
Yes — this is the core of how we keep an acquisition running smoothly. Before migrating anything, we set up coexistence between the two tenants so people can email each other normally, look up each other's calendar availability, and find each other in a shared directory. That collaboration continues throughout the project, so the two teams operate as one well before the technical migration is finished.
What happens to the acquired company's domain and email addresses?
It depends on your plan. You might keep the acquired company's domain so their addresses stay the same, or rebrand everyone onto your primary domain over time — both are common, and we'll support whichever you choose. The key technical point is that a domain can only live in one Microsoft 365 tenant at a time, so moving it from the old tenant to yours is a carefully timed step. We plan that window precisely so the switch happens cleanly without interrupting mail.
Will we lose any emails, files, or Teams content?
No. We migrate full copies into your tenant and validate that everything has arrived before the source tenant is decommissioned, with a final sync at cutover to capture last-minute changes. The old environment stays in place until you've confirmed the merge is complete, so there's always a fallback. Nothing is deleted on a hope.
Can you migrate our Teams chats and channels?
We migrate Teams, their channels, the files within them, and their structure into your tenant, so team collaboration continues in the new home. It's worth being upfront that private one-to-one chat history is the most technically limited part of any tenant-to-tenant move — the platform simply doesn't migrate it as cleanly as channels and files. We'll set clear expectations during planning so there are no surprises, and advise on the best approach for your situation.
How do you handle duplicate accounts or people with the same name?
Carefully, and during planning rather than mid-migration. We map every user from the source tenant to their place in your tenant, and where names or addresses clash — two people called John Smith, or an address already in use — we agree a naming convention with you up front and apply it consistently. This avoids the confusion and mis-delivered email that a rushed merge often causes.
We have a deal close date — can you work to a deadline?
Yes, and we expect to. Acquisitions and divestitures run to fixed timelines, often with legal or transitional-service deadlines attached. We build the migration plan backwards from your close date, sequence the work to hit the milestones that matter, and keep you updated on progress against the schedule. If a date is genuinely tight, we'll tell you honestly what's achievable rather than over-promising.
How long does a tenant-to-tenant migration take?
It varies widely with the number of users and how much data and Teams content is involved, but most are measured in weeks rather than days — the coexistence setup, workload migration, and domain move each need their own careful steps. After assessing both tenants we'll give you a realistic timeline mapped to your deal deadline, along with a wave-by-wave plan so you can see exactly how we'll get there.
Let's Talk
Let's bring your two tenants together.
Book a free migration call — tell us about the acquisition or merger, and we'll map a coordinated, deadline-driven plan to combine both environments.
30 minutes · No commitment · We'll map the merge around your deal date