Microsoft 365 Copilot turns on Claude for UK tenants on December 9

Microsoft will turn on Anthropic's Claude models in Microsoft 365 Copilot by default for organizations in the UK on December 9. According to Message Center post MC1546435, the change applies to every UK tenant whose admins have not chosen a setting yet. As The Register puts it, leaving the setting untouched means opting in. Nothing changes for companies and public bodies in the EU, where Claude stays off until an admin turns it on.

Why the EU is still excluded

Microsoft explains the reason on its Claude documentation page. Claude models in Copilot, Researcher, Copilot Studio and the Power Platform are "currently excluded from the EU Data Boundary," Microsoft's commitment to process customer data inside the EU. For customers in the EU, the EFTA and the UK, the setting has therefore defaulted to No users. In other commercial regions, Claude is already on by default, and The Register reports that Anthropic processes the data in the US.

The UK is not part of the EU Data Boundary, so Microsoft is dropping the exception there. At the same time, it is retiring the option to allow Claude only in Copilot in the Microsoft 365 apps, which means tenants without their own selection move to all users on December 9. UK admins who want Claude to stay disabled or limited need to select No users, or specific users and groups, before that date.

What admins should check

The setting is in the Microsoft 365 admin center under Copilot, Settings and AI providers operating as Microsoft subprocessors. Only AI administrators and global administrators can change it. Organizations in the EU that previously opted in under Anthropic's separate commercial terms need to opt in again, according to Microsoft.

Microsoft handles Anthropic models with Data Retention, such as Claude Fable 5 and Claude Mythos 5, separately. Anthropic's own terms apply to them instead of Microsoft's data protection commitments. Anthropic keeps most inputs and outputs for up to 30 days, and admins still have to enable these models on their own. Neither Microsoft's page nor the Message Center post mentions Microsoft 365 Personal or Family, since both only cover managed work accounts. Our guide to turning off Copilot and Recall explains how to remove Copilot from Windows 11.