What is a migration wave in a tenant-to-tenant migration?
Checked October 27, 2026 by Accred Consulting
A migration wave is a scheduled group of users, and the mailboxes, OneDrive accounts, sites, and teams they work in, that you move from one Microsoft 365 tenant to another together. Waves keep each cutover small enough to support, put people who share content in the same move, and leave time to fix errors before the next group. Most projects run a small pilot first, then waves by department or location.
How to plan waves
- Inventory and map every source object to its destination: users, mailboxes, OneDrive accounts, sites, teams, and groups.
- Run read-only prechecks so blockers, such as mailboxes on hold, surface before any move.
- Move a pilot wave of a few willing users and check mail, files, and calendars end to end.
- Group the rest by who works together, so shared mailboxes, calendars, and team sites move with their people.
- Size each wave to what your support team can handle on cutover day, and leave a gap between waves to fix errors.
- Validate each wave, then cut over mail flow and sign-in for those users.
Microsoft’s native limits that shape waves
- Cross-tenant mailbox moves are created as migration batches with the New-MigrationBatch cmdlet, so a wave maps naturally to one or more batches.
- Mailboxes on any type of hold are not migrated, and their move is blocked.
- Up to 4,000 OneDrive accounts can be scheduled for migration in advance at a time.
- Cross-tenant OneDrive and SharePoint moves cannot run incremental or delta passes, so schedule them close to cutover.
- Each migrated user needs a Cross Tenant User Data Migration license; migrations fail without it.
Tools that plan waves
Microsoft’s native tools run each batch from PowerShell and have no wave planner. Accred Migrate organizes each client’s project by tenant, wave, and workload, and is in early access. For other tools, see the tenant-to-tenant migration tool comparison.
Questions
How many users should be in a migration wave?
There is no fixed number. Size each wave to what your team can support on cutover day and keep people who share mailboxes, calendars, and sites together. Start with a small pilot.
Can I run a delta pass for OneDrive in a tenant-to-tenant move?
Not with Microsoft’s native cross-tenant OneDrive migration, which cannot run incremental or delta passes. Third-party tools may offer them.
Why did a mailbox fail to migrate?
Common causes in Microsoft’s native mailbox migration include a hold on the mailbox, which blocks the move, and a missing Cross Tenant User Data Migration license.
Sources
- Cross-tenant mailbox migration · Microsoft Learn
- Cross-tenant OneDrive migration · Microsoft Learn
- Cross-tenant SharePoint migration · Microsoft Learn
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