Microsoft Copilot in Microsoft 365 can work with guest users from other organizations. By default, guest users cannot access Copilot features. An admin must configure cross-tenant access settings and assign the correct licenses. This article explains how to enable Copilot for B2B guest users in the Microsoft Entra admin center and the Microsoft 365 admin center.
Guest users receive a Copilot license through their home tenant. The resource tenant where they collaborate must allow inbound Copilot data access. Without these settings, guest users see an error message that Copilot is unavailable. The steps below cover both the Entra ID configuration and the Microsoft 365 license assignment.
You will also learn how to verify that guest users can use Copilot in Microsoft Teams, Word, and SharePoint. The guide applies to Microsoft 365 E3, E5, and Copilot for Microsoft 365 licenses.
Key Takeaways: Enabling Copilot for B2B Guest Users
- Microsoft Entra admin center > External Identities > Cross-tenant access settings: Configure inbound settings to allow Copilot data for guest users from specific partner tenants.
- Microsoft 365 admin center > Users > Active users > Guest user profile: Assign a Copilot for Microsoft 365 license to each guest user who needs access.
- Microsoft 365 admin center > Billing > Licenses > Copilot for Microsoft 365: Ensure you have enough available licenses for guest users before assigning them.
Why Guest Users Cannot Access Copilot by Default
Microsoft Entra ID uses cross-tenant access policies to control what data and services are shared with external users. Copilot for Microsoft 365 relies on Microsoft Graph to generate responses. Guest users from another tenant cannot access Graph data in the resource tenant unless an admin explicitly allows it.
The default cross-tenant access settings block inbound Copilot data for all external users. This means even if a guest user has a Copilot license from their home tenant, they cannot use Copilot in the resource tenant. The resource tenant must configure inbound access settings to allow Copilot data for each partner tenant.
Additionally, the guest user must have a Copilot for Microsoft 365 license assigned in the resource tenant. The license can come from the resource tenant’s license pool or from the guest user’s home tenant if the resource tenant allows it. The steps below assume the resource tenant provides the license.
Steps to Enable Copilot for B2B Guest Users
You need two roles to complete these steps: Global Administrator in Microsoft Entra ID and License Administrator in Microsoft 365. Complete the Entra ID configuration first, then assign licenses.
Step 1: Configure Cross-Tenant Access Settings in Microsoft Entra ID
- Sign in to the Microsoft Entra admin center
Go to https://entra.microsoft.com and sign in with an account that has the Global Administrator role. - Navigate to External Identities > Cross-tenant access settings
In the left navigation, select External Identities and then Cross-tenant access settings. - Select the partner tenant
Under Organizational settings, choose the partner tenant whose guest users need Copilot access. If the tenant is not listed, select Add organization and enter the partner tenant ID or domain name. - Configure inbound access
Select the partner tenant row, then select Inbound access. Go to the Trust settings tab. Under Copilot for Microsoft 365, select Allow inbound Copilot data. This setting allows guest users from that partner tenant to send Copilot queries to your tenant’s Microsoft Graph. - Save the changes
Select Save at the top of the page. Repeat steps 3-5 for each partner tenant that needs Copilot access.
Step 2: Assign a Copilot for Microsoft 365 License to the Guest User
- Sign in to the Microsoft 365 admin center
Go to https://admin.microsoft.com and sign in with an account that has the License Administrator role. - Go to Users > Active users
In the left navigation, select Users and then Active users. - Find the guest user
In the user list, locate the guest user account. Guest users are marked with a globe icon. Select the user’s name to open their profile. - Open the Licenses and apps tab
In the user profile, select the Licenses and apps tab. - Assign the Copilot license
Select Licenses and then check the box for Copilot for Microsoft 365. If you do not see this license, you need to purchase it first. Go to Billing > Purchase services to buy Copilot licenses. - Save the assignment
Select Save changes. The guest user now has a Copilot license assigned in the resource tenant.
Step 3: Verify Guest User Access
- Ask the guest user to sign in
Instruct the guest user to sign in to Microsoft Teams or Word using their home tenant credentials. - Open Copilot
In Teams, select the Copilot icon in the left navigation. In Word, open a document and select the Copilot icon in the ribbon. - Send a test prompt
Type a prompt such as “Summarize the latest file from the shared SharePoint site.” If Copilot returns a response, the configuration is complete. If the user sees an error, check the cross-tenant access settings and license assignment.
If Guest Users Still Cannot Access Copilot
Copilot shows “Copilot is not available for your account”
This error usually means the license is not assigned or the cross-tenant access setting is not applied. Verify that the guest user has the Copilot for Microsoft 365 license in the resource tenant. Also confirm that the inbound Copilot data setting is enabled for the partner tenant in Entra ID.
Copilot returns generic responses instead of tenant-specific data
Generic responses indicate that Copilot cannot access Microsoft Graph data in the resource tenant. This happens when the inbound Copilot data setting is set to block or not configured. Go back to Entra ID > External Identities > Cross-tenant access settings and confirm that Allow inbound Copilot data is selected for the partner tenant.
Guest user cannot sign in or is not recognized
The guest user invitation may have expired or been revoked. Go to Microsoft Entra ID > External Identities > All users and verify the guest user status. If the status shows “Pending acceptance,” resend the invitation from the Microsoft 365 admin center.
Copilot for Microsoft 365: Guest User vs Full User Access
| Item | Guest User Access | Full User Access |
|---|---|---|
| License requirement | Copilot for Microsoft 365 license assigned in resource tenant | Copilot for Microsoft 365 license assigned in home tenant |
| Cross-tenant access setting | Inbound Copilot data must be allowed | Not required |
| Microsoft Graph data access | Limited to shared content in the resource tenant | Full access to home tenant data and shared resource tenant data |
| Admin role needed to enable | Global Administrator in Entra ID and License Administrator in M365 | License Administrator only |
| Supported apps | Teams, Word, SharePoint, Outlook | All Copilot-integrated apps |
Guest users have more restricted data access than full users. They can only query content that has been explicitly shared with them or that is in shared locations like SharePoint sites where they have permissions. Full users can access all content in their home tenant.
Guest users also cannot use Copilot in Microsoft 365 Chat or Copilot in Teams meetings unless they are invited to the meeting as a participant. The guest user must have at least View permissions on the content they want Copilot to summarize.
Conclusion
You can now enable Copilot for B2B guest users by configuring cross-tenant access settings in Microsoft Entra ID and assigning a Copilot for Microsoft 365 license in the Microsoft 365 admin center. The key setting is the inbound Copilot data toggle under the partner tenant’s trust settings. After configuration, guest users can use Copilot in Teams, Word, and SharePoint to summarize shared documents and conversations. For advanced scenarios, consider using Microsoft Entra ID Governance to automate license assignment for guest users through access packages.