Microsoft Entra B2B guest user
Answer: A B2B guest is a user object in a resource tenant that represents an external identity authenticated by its home identity provider; access is governed in the resource tenant.
Administrator playbook
Decide, verify, and document
Use the curated answer as a starting point, then prove the outcome against the target tenant or device.
What it means
- The resource tenant stores a local user object
- Authentication can occur in the user's home tenant or another configured identity provider
- Cross-tenant access settings and Conditional Access can affect the session
What to check next
- Confirm home identity and resource tenant
- Review invitation/redemption state and user type
- Check cross-tenant access, Conditional Access, and resource assignment
Verify success
- Confirm the object type and identifier in the authoritative tenant.
- Compare the portal value with Microsoft Graph or the local device state.
- Use IDs—not display names—when proving that two references point to the same object.
Escalate when
- Two portals or APIs return conflicting identifiers for the same expected object.
- The issue crosses tenant or cloud boundaries.
- A production authorization decision depends on the object relationship.
Copyable admin briefAnswer, next checks, source, and review date
Inspect Microsoft Graph context
Get-MgContext | Select-Object ClientId,TenantId,Account,AuthType,ScopesRead-only. Useful when a term or identifier is being interpreted in the wrong tenant.
Evidence to preserve
- Object location
- Resource tenant
- Authentication
- Home identity provider
- Access control
- Resource tenant
- Tenant ID and cloud
- Object type and object ID
- User, app, or device context
- Where the value was observed