TL;DR
Microsoft will turn on Anthropic’s Claude models for UK Copilot tenants on 9 December unless an administrator has already chosen a setting, The Register reported on 10 November. Microsoft’s documentation says the data involved is processed by Anthropic in the US. UK organisations have four weeks to decide whether that fits their data-handling rules.
What is changing
Claude already runs by default for most commercial Microsoft customers, with Anthropic acting as a Microsoft subprocessor. The exceptions include the UK, the EU and the EFTA states.
The UK loses that status because it sits outside Microsoft’s EU Data Boundary, in place since early 2023. From 9 December, Claude is enabled for any UK tenant where no setting has been chosen. Admins can switch it off, but doing nothing counts as opting in.
Microsoft is also withdrawing the option that limited Claude to Microsoft 365 apps only. Microsoft said the change “affirms Microsoft’s commitment to offering choice between leading AI models while maintaining enterprise-grade security and compliance.”
What admins need to check
For a UK organisation, the practical question is whether sending Copilot data to a US subprocessor is allowed under its own policies, contracts and data protection assessments. Public bodies, law firms, healthcare providers and others with strict residency commitments may find it is not, and should set the toggle before the deadline rather than after.
What it means
This lands in a week when an FOI found 10 of 11 Cabinet Office AI tools run on US firms’ models, and a government spokesperson replied that tools built by GDS and i.AI are model-agnostic. Microsoft’s change shows how that dependency can grow by default, through a vendor setting rather than a procurement decision.
In our view, opt-out defaults for a new data processor sit awkwardly with how UK organisations are expected to manage processors. IT and data protection teams should review the Copilot admin settings now, record the decision either way, and update their processor records if Claude stays on.