GPT-6.1 Sol and Claude Sonnet 5.5 available in Copilot
- Maxime Hiez
- Copilot
- 06 Oct, 2026
Introduction
Microsoft Copilot has been rolling out, since September 30, 2026, two new frontier models : GPT-6.1 Sol from OpenAI and Claude Sonnet 5.5 from Anthropic. This rollout follows that of Claude Opus 5.5 and GPT-6 Sol, integrated earlier this month, and continues the expansion of the model choice offered to Copilot users.
Where the models are available
The rollout happens in two stages :
- Copilot Cowork and Copilot Studio : Available starting September 30, 2026, billed on a pay-as-you-go basis
- Word, Excel, PowerPoint, and Copilot Chat : Gradual rollout within the week following the announcement, included in the user’s license (USL)
In Word, Excel, PowerPoint, and Chat, usage limits apply, but they’re sized to cover typical daily use : the vast majority of users shouldn’t reach them. When approaching a limit, the user gets a notification in the app and can keep going by switching to Auto mode or selecting another available model.
What’s changing
Microsoft’s argument stays the same as with previous rollouts : more model choice means more flexibility to match the experience to the task at hand. With Work IQ, Copilot grounds GPT-6.1 Sol’s and Claude Sonnet 5.5’s responses in the tenant’s files, meetings, conversations, and business data, while respecting existing permissions.
What administrators should know
No action is required for eligible users to access these two models, access is enabled by default. Two separate conditions, however, govern their actual availability :
- Claude Sonnet 5.5 : Requires the Anthropic subprocessor to be enabled for the organization
- GPT-6.1 Sol : Requires the OpenAI subprocessor to be enabled for certain Copilot surfaces
It’s recommended to check the status of these two subprocessors before communicating model availability to users, to review internal AI usage guidelines, and to brief support teams on the usage-limit notifications they might need to explain.
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Conclusion
With GPT-6.1 Sol and Claude Sonnet 5.5, Copilot continues to expand its multi-vendor catalog with no action required from administrators by default. The one real point of attention remains the Anthropic and OpenAI subprocessor configuration, which governs effective access to each of the two models depending on the Copilot surface in use.
Sources
Microsoft Learn - Microsoft 365 Copilot release notes
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