Using classic Outlook for Windows in business environments
Dear @Leah Hawley,
Thank you for posting your question in the Microsoft Q&A forum.
I understand that you’d like each organization to have its own account and separate billing. You can absolutely have separate Microsoft 365 accounts and billing for both entities.
Here is some information that will help clarify your question:
To help clarify, let’s refer to Company A as your organization and Company B as your sister company.
Step 1: Create separate tenants (accounts)
Each company needs its own Microsoft 365 tenant. That means setting up:
- Set up a new Microsoft 365 tenant for Company A.
- Keep Company B in its existing tenant.
This ensures full data and administrative separation.
Step 2: Set up independent billing profiles
After creating separate tenants, you’ll also need distinct billing setups:
Each tenant uses its own billing profile and payment method.
In the Microsoft 365 admin center, you can assign the correct subscription to each tenant and pay separately.
If you're managing both tenants, you can optionally use Associated Billing Tenants under a Microsoft Customer Agreement to oversee billing from a central account, while keeping invoices and payment methods independent.
Step 3: Migrate users & data (If needed)
If any users or data currently belong to Company A but are in Company B’s tenant:
- Prepare a new tenant subscription for Company A.
- Manually migrate mailboxes, OneDrive, SharePoint and other data to the new tenant.
Note: It's a manual operation involving setting up a new domain, migrating mailboxes, moving files and reconfiguring users.
Once complete, remove Company A’s domain from Company B’s tenant.
Step 4: Configure Outlook & OneDrive
To maintain separation for end-users:
Use separate Outlook profiles (via Control Panel > Mail > Show Profiles) to ensure each account opens under the right tenant.
Ensure users sign into OneDrive with the correct business account associated with their tenant, keeps their files siloed and private to that company.
Additional information is available in the following resources:
Manage billing across multiple tenants in the Microsoft 365 admin center | Microsoft Learn
Transfer data manually between two accounts - Microsoft 365 admin | Microsoft Learn
Optional: Contact Microsoft Support
Additionally, you may consider asking your IT department to reach out to Microsoft Support for further assistance with this issue. A support engineer can guide them in the right direction and if any issues occur, they can verify the backend configurations and run the necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.
As forum moderators, we don’t have access to the detailed logs or backend systems needed to troubleshoot this effectively due to privacy and security constraints. Our primary role is to guide users toward the appropriate resources and support channels. While we may not have visibility into performing deeper backend analysis, we’ll continue doing our best to support you within the scope of our responsibilities.
- Your IT department can create a support ticket from Microsoft 365 Admin Center > Support > Help & Support.
- Microsoft provides customer service phone numbers based on your region. They can find the appropriate contact number here: Customer service phone numbers - Microsoft Support
I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this.
Thank you for your patience and understanding. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have any extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.