Microsoft 365 Tenant-to-Tenant Migration Services
Moving from one Microsoft 365 tenant to another is rarely just a data migration.
A tenant-to-tenant migration usually sits behind a bigger business change: a merger, acquisition, divestment, restructuring exercise, rebrand or tenant consolidation project. The technical work matters, but the real challenge is making sure email continues to flow, users can still work, files remain accessible, permissions make sense, and the business does not lose confidence halfway through the project.
EJK Consultancy helps organisations plan and deliver Microsoft 365 tenant-to-tenant migrations across Exchange Online, SharePoint Online, OneDrive, Microsoft Teams and Microsoft Entra ID.
We work directly with your internal teams to understand the current environment, plan the migration properly, manage the cutover, and support users after the move.
When Do Organisations Need a Tenant-to-Tenant Migration?
Tenant-to-tenant migrations are usually required when the Microsoft 365 environment no longer matches the structure of the business.
This often happens after a merger or acquisition, where one organisation needs to bring users, mailboxes and data into an existing Microsoft 365 tenant. It can also happen when a business sells a division and needs to separate users and data into a new tenant.
Other projects are driven by consolidation. Over time, larger organisations can end up with multiple Microsoft 365 tenants because of previous acquisitions, regional operations or historic IT decisions. That can make licensing, security, compliance and administration harder than they need to be.
Typical scenarios include:
The important point is that the migration approach should be shaped by the business scenario. A clean acquisition into an existing tenant is not the same as separating a division from a parent company, and the planning should reflect that.
What Is Usually Involved In A Tenant-to-Tenant Migration?
A Microsoft 365 tenant migration can involve several different workloads. Some organisations only need email migrated. Others need a full migration covering mailboxes, files, Teams, SharePoint, users, groups, domains, permissions and security settings.
EJK Consultancy can support migrations across the core Microsoft 365 services, including Exchange Online, SharePoint Online, OneDrive for Business, Microsoft Teams and Microsoft Entra ID.
Exchange Online Migration
Email is usually the most visible part of the project. If mail flow breaks, users notice immediately.
A well-planned Exchange Online migration considers not just mailbox data, but shared mailboxes, calendars, contacts, distribution groups, resource mailboxes, aliases, forwarding rules, accepted domains and the timing of DNS changes.
The aim is to make the email cutover as clean as possible, with users understanding what is changing, when it is changing, and what they need to do after migration.
SharePoint and OneDrive Migration
SharePoint and OneDrive migrations are often more complex than they first appear.
It is not just a case of copying files from one place to another. Permissions, sharing links, site structures, document libraries, ownership, metadata and historic working practices all need to be understood before anything is moved.
This is also a good opportunity to clean up poor structure, stale content and inherited permissions rather than blindly moving years of clutter into the new tenant.
Microsoft Teams Migration
Teams migrations need careful handling because Teams is closely connected to Microsoft 365 Groups, SharePoint, Exchange and user identity.
In many migrations, the files stored behind Teams are more important than the chat history. In others, channel structure, membership and continuity of collaboration are key requirements.
EJK Consultancy will help you decide what should be migrated, what should be recreated, and what should be left behind.
Identity, Domains and Access
The hardest part of many tenant migrations is not the data. It is identity.
User accounts, domains, authentication methods, Entra ID configuration, Conditional Access, security groups, Microsoft 365 Groups and admin roles all need proper planning.
Moving a domain between tenants is also a critical step. If it is handled badly, users can experience email disruption, sign-in problems and confusion around usernames.
Common Tenant-to-Tenant Migration Risks
Most tenant migration problems come from poor discovery or rushed planning. The migration tool is only one part of the project. The bigger risks usually sit around dependencies that were not identified early enough.
Common issues include:
- Domains that cannot be released cleanly from the source tenant
- Unexpected mail flow dependencies
- Shared mailboxes and distribution groups that were missed during discovery
- Users with large or complex mailboxes
- SharePoint sites with unclear ownership
- OneDrive data belonging to leavers or inactive users
- Teams structures that do not map neatly into the target tenant
- Third-party applications using Microsoft 365 authentication
- Conditional Access policies blocking users after migration
- Licensing gaps in the target tenant
- Poor user communication before cutover
A good migration is not just about moving data. It is about reducing surprises.
Our Tenant Migration Approach
EJK Consultancy follows a practical migration approach based on discovery, planning, controlled execution and post-migration support.
1. Discovery and Assessment
We start by reviewing both the source and target Microsoft 365 tenants. This includes users, mailboxes, data volumes, domains, SharePoint sites, Teams, licensing, security settings and known business dependencies. The purpose of discovery is simple: find the problems before they become live migration issues.
2. Migration Planning
Once the environment is understood, we create a migration plan covering scope, timelines, tooling, responsibilities, risks, testing, communication and cutover sequencing. This is where key decisions are made, including whether the migration should happen in phases, whether users should be moved in waves, and how much clean-up should happen before migration.
3. Pilot Migration
A pilot migration helps validate the approach before the wider business is affected. This usually involves a small group of users or a controlled subset of data. The pilot confirms the migration process, user experience, mail flow, access, permissions and support requirements.
4. Migration Execution
The production migration is then carried out in a controlled way using appropriate Microsoft and third-party migration tooling. Depending on the size and complexity of the project, this may involve staged migration, weekend cutovers, phased business unit moves, or a more direct migration approach.
5. Post-Migration Support
After migration, users often need help with Outlook profiles, OneDrive sync, Teams access, shared mailbox access, mobile devices and general sign-in issues. We remain involved after the move to resolve issues quickly and make sure the target environment is stable.
How Much Does A Tenant-to-Tenant Migration Cost?
The cost of a tenant-to-tenant migration depends on the number of users, the data involved, the complexity of the Microsoft 365 environment, migration tooling, domain requirements and the level of support needed.
As a guide, our Microsoft 365 Migration Assessment prices tenant-to-tenant projects in the following ranges:
| User Count | Estimated Project Range |
|---|---|
| Under 50 users | typically £8,000 to £11,000 |
| 50 to 250 users | typically £14,000 to £20,000 |
| 250 to 500 users | typically £20,000 to £28,000 |
| 500 to 1,000 users | typically £28,000 to £38,000 |
| More than 1,000 users | typically £40,000 to £55,000 |
These figures are intended as planning estimates. A smaller tenant with complex SharePoint, Teams and domain requirements may require more work than a larger tenant with email-only scope.
Estimate Your Project Costs
Planning a tenant-to-tenant migration? Use our Microsoft 365 Migration Assessment to estimate the likely project cost based on your user numbers, migration scope and complexity.
Why Work With EJK Consultancy?
EJK Consultancy is led by an experienced Microsoft 365 consultant with 25 years in IT infrastructure, cloud services and business systems.
You are not passed between salespeople, account managers and junior engineers. You work directly with someone who understands the technical detail and can explain the risks clearly.
EJK Consultancy brings hands-on experience across Microsoft 365 migrations, Exchange Online, SharePoint Online, Microsoft Teams, Microsoft Entra ID, security, compliance and tenant administration.
We are Microsoft certified across Microsoft 365 administration and Exchange Online administration.
The approach is straightforward: understand the environment properly, plan the migration carefully, avoid unnecessary disruption, and give the business a clear route through the project.
Tenant-to-Tenant Migration FAQs
Common questions about moving users, data and services between Microsoft 365 tenants.
Planning a Microsoft 365 tenant-to-tenant migration?
Speak directly with an experienced consultant to assess your tenant environment and plan a smooth, risk-managed migration.