The Top 6 Considerations for Migrating between Office 365 Tenants – Part Three

For the final article of this Migrating between Office 365 Tenants series, we’ll look at the last three considerations: ensuring you’re going to the right tenant, end user devices, and user communications and education.

In Part One, we analysed the prerequisites needed for an Office 365 migration, such as planning what needs and can be moved. In Part Two, we started looking at the next three considerations for an Office 365 migration: domains, identity creation and velocity.

Make sure you’re going to the right tenant

Choosing a tenant is normally only a question that will come up in a Merger, Acquisition and Divestiture (MAD) scenario, and although many times the answer appears obvious, don’t be quick to judge.

You will typically see three options for Office 365 tenant selection in a merger/acquisition scenario: Tenant A (Company A), Tenant B (Company B), Tenant C (New Tenant).  

You will need to evaluate how much complexity and volume there is to migrate into your target tenant, and how much disruption it will cause by introducing new users and data. This is because there could be duplicate site collections that need to be consolidated or renamed before migration.

Normally the “parent” company with an existing tenant will take a default position that the target should be their existing tenant. However, it’s sometimes worth digging deeper and evaluating whether the integration of the two businesses could warrant a separate new tenant, then you’d move the old data from both legacy organisations into a fresh tenant.

Although this will increase your effort to move the data for all users rather than a subset, it could provide more long-term value by removing technical debt that has previously been accrued in that environment. It also gives you the opportunity to reset some poor or out of date decisions made.

I would strongly recommend you consider all angles that are relevant when thinking about your target tenant and be open to a decision that may make you or other stakeholders uncomfortable.

User communications and education

A big mistake within organisations completing a tenant to tenant migration is “Well they’re already using Office 365, so we don’t need to worry about user comms…”

Your users will be familiar with the tools because they haven’t changed, however, the migration is going to impact them differently. They need to be informed: which of their content is going to be available in the new environment and when, what the migration experience will be like, and who they’ll be able to see in the environment post-migration. Whether you’re taking users out of a larger environment, or consolidating two groups of users and their content, it has more impact than you anticipate.

Learn more: Top Five Ways to Prepare for Your Next Office 365 Tenant Migration

There is likely to be impact from this migration, and this type of migration is almost always happening around other wider business disruption. So ensure your users understand the benefits of the migration. For example, depending on your MAD activity, this could be more independence and freedom from leaving a larger organisation’s strict controls, or, additional benefits because they have access to people and content from a wider organisation. You can use your Office 365 migration to spin an interesting news story to your colleagues!

Finally, you must ensure that users know where to go and who to contact when there are unintended consequences from the migration – because believe me, this will happen. Clear communication on how to contact support, where quick start guides, or other documentation can be obtained from is vital. Even if you’re just migrating users from one Office 365 tenant to another.


These are just my top 6 considerations when planning an Office 365 tenant to tenant migration, but don’t consider it exhaustive. The most important thing is that you consider your business needs and requirements and try to consider all the angles before making decisions you regret. Be open the views of others, and always prepare for the unexpected.

To learn more about this topic, check out this whitepaper ‘Top Five Ways to Prepare for Your Next Office 365 Tenant Migration’

About the Author

Mike Parker

Mike is a Technical Architect at Content and Code, a multiple award-winning Microsoft Partner. He has spent the last five years working closely with Microsoft 365 technologies. Mike’s primary area of focus is in the delivery of the Microsoft 365 suite, including the Office 365 suite and Enterprise Mobility + Security, for a range of global enterprise clients. Mike blogs at, speaks at internal and public events when time allows!

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