Introduction
If you work in IT long enough, you’ll eventually face a tenant-to-tenant migration. It usually happens after a merger, an acquisition, or a big reorg. On paper, it sounds simple-move data from one Microsoft 365 tenant to another. In reality? It’s one of the more complex projects you’ll run.
The tricky part is that it’s not just about data. You’re dealing with identities, permissions, apps, compliance, and people’s day-to-day work. If things go wrong, users notice immediately and trust me, they will let you know.
The good news: with a solid plan, you can avoid the usual headaches. Here’s a checklist to keep your migration on track.
Why Tenant-to-Tenant Migration Gets Messy
Most first-time migration projects underestimate the scope. Here’s what usually complicates things:
- Identity and access. Users need to log in without issues. Break this, and nothing else matters.
- Applications. Power Apps, Teams integrations, and third-party connectors don’t magically move with you. Some need to be rebuilt.
- Compliance. Legal holds, retention policies, and data residency rules can’t be ignored.
- User experience. Even a few hours of downtime can cause frustration (and a lot of help desk tickets).
That’s why Microsoft and experienced migration partners recommend treating T2T migration as a business project with IT at the core, not just an IT task list.
The Tenant-to-Tenant Migration Checklist
Here’s what to include in your plan.
1. Define the Scope and Objectives
Ask the basic questions up front:
- Why are we migrating? (Acquisition? Consolidation? Compliance?)
- What’s in scope? (Just Exchange and OneDrive? Or Teams, SharePoint, and apps too?)
- What does success look like? (Minimal downtime? Zero data loss? Fast cutover?)
Clarity here prevents scope creep later.
2. Run a Pre-Migration Assessment
Think of this as your IT inventory. Document:
- Mailboxes, SharePoint sites, Teams, OneDrive.
- Power Apps, Power Automate flows, and custom connectors.
- Security and compliance policies (retention, DLP, eDiscovery).
Spot the blockers now-like oversized mailboxes or unsupported apps-so you’re not scrambling later.
3. Build a Realistic Migration Plan
With the T2T migration assessment done, map out how you’ll get from A to B:
- Timeline: Phased vs. “big bang” cutover.
- Communication: Let users know what’s happening and when. No surprises.
- Risk plan: Define rollback options in case something fails.
- Stakeholders: Make sure IT, compliance, and business teams are aligned.
A written plan reduces last-minute fire drills.
4. Identity and Access Management
This is the heart of the migration. Without working identities, users are stuck.
- Sync users and groups correctly between tenants.
- Carry over group memberships, licenses, and roles.
- Double-check authentication and conditional access policies.
If you only get one thing perfect, make it identity.
5. Migrate Core Workloads
Here’s where the heavy lifting happens:
- Email & Calendars: Move Exchange mailboxes, calendars, and distribution lists.
- Collaboration: SharePoint, OneDrive, and Teams data. Don’t forget chats and channel history.
- Power Platform: This part hurts—Power Apps and flows often require manual export/import and reconfiguration.
- Third-party tools: Re-establish all integrations and connectors in the new tenant.
Pro tip: Treat Power Apps like their own project. They don’t migrate cleanly, and trying to “wing it” rarely works.
6. Test, Validate, and Support
Don’t declare victory the moment data moves. You still need to:
- Run tests to confirm permissions, data, and apps work.
- Pilot with a small user group before going wide.
- Offer “hypercare” support during cutover so issues get fixed fast.
Best Practices That Save You Headaches
A few things experienced IT leaders always do:
- Communicate early and often with end users.
- Test in a safe environment before production.
- Expect manual fixes (especially with apps and connectors).
- Bring in migration experts if you don’t have in-house experience.
Common Pitfalls to Watch Out For
Based on projects I’ve seen, here are the usual mistakes:
- Assuming everything can be automated.
- Forgetting about compliance or governance settings.
- Neglecting user adoption and training.
- Underestimating how long cutover really takes.
Avoid these Microsoft 365 T2T migration common challenges, and you’re already ahead of the curve.
Discover why most M&A deals fail without a solid tenant migration strategy-and learn how a seamless tenant-to-tenant migration can make all the difference.
Conclusion
A tenant-to-tenant migration is about more than moving workloads. It’s about keeping the business running smoothly while everything underneath shifts.
With the right checklist and the right guide, you can avoid downtime, keep your users happy, and reduce risk.
At Netwoven, we’ve helped organizations handle these migrations without the drama-balancing speed, security, and user experience.
Thinking about a tenant migration?
Explore Netwoven’s Tenant-to-Tenant Migration Services or schedule a consultation today.
