Calendar Problems

How to Share or Merge Calendars Across Microsoft 365 Tenants

Aamir Naveed Akram Oct 16, 2026 869 views

Question details

Users want to automatically synchronize or merge meetings from separate user calendars across different Microsoft 365 tenants into one shared calendar.

How to Share or Merge Calendars Across Microsoft 365 Tenants

Product: Microsoft Outlook
Device & OS: not provided
Scenario: Managing schedules for an organization operating across multiple Microsoft 365 tenants.
Observed behavior: Outlook currently does not support automatic full cross-tenant synchronization or automatic calendar merging.

Before you start

Verify your administrative permissions in Microsoft 365, as cross-tenant sharing policies may need to be enabled by an IT administrator before individual users can share their calendars.

Solution 1Recommended

Manually Share Individual Calendars Between Tenants

Since automatic merging is not supported, the best approach is to share individual calendars manually and add them to your Outlook view.

Microsoft Outlook does not currently offer a built-in feature to automatically merge calendars across multiple Microsoft 365 tenants. However, you can achieve visibility by sharing individual calendars across tenants, provided the organization's sharing policies allow external access.

Open Outlook Calendar

Launch Microsoft Outlook and navigate to the Calendar view from the bottom left navigation pane.

Share the Calendar

Click on the 'Share Calendar' option in the Home ribbon and select the calendar you wish to share with users in the other tenant.

Set Permissions

Enter the email addresses of the users in the external Microsoft 365 tenant, assign the appropriate permission level (e.g., 'Can view all details'), and click 'Send'.

Add the Shared Calendar

The recipient must open the sharing invitation email and click 'Accept' to add the calendar to their Outlook view.

Manually Share Individual Calendars Between Tenants

Submit Feedback: If your organization strictly requires automatic cross-tenant merging, consider submitting a feature request through the Microsoft Feedback portal for future consideration.

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Frequently Asked Questions

Can I use Power Automate to merge calendars across Microsoft 365 tenants?

Yes, advanced users can set up custom Power Automate flows to copy events from a calendar in one tenant to a calendar in another. However, this requires careful configuration of connections and may duplicate events rather than truly syncing them bidirectionally.

Why am I unable to share my Outlook calendar with a different tenant?

Your organization's IT administrator may have disabled external sharing policies in the Microsoft 365 admin center. Cross-tenant sharing must be explicitly permitted in the organization relationships settings.

Will Microsoft add cross-tenant calendar syncing in the future?

Microsoft continually updates its Microsoft 365 roadmap. Currently, full automated cross-tenant synchronization isn't a standard feature, but users are encouraged to upvote this request on the Microsoft Feedback portal to increase its priority.

Outlook & Email Problems