MC1483844: Microsoft Copilot Adds GPT‑6.1 Sol and Claude Sonnet 5.5 Models Across Microsoft 365 Apps

📢 Official Microsoft Message Center Announcement

Updated October 22, 2026: We have updated the content. Thank you for your patience. 

[What and Why:]

To give users more choice and flexibility when working with AI in Microsoft Copilot, we’re expanding the set of AI models available in Microsoft Copilot.

Starting today, GPT-6.1 Sol and Claude Sonnet 5.5 begin rolling out with usage-based billing in Cowork and Microsoft Copilot Studio.

GPT-6.1 Sol and Claude Sonnet 5.5 will also begin rolling out in phases across Word, Excel, PowerPoint, and Chat in the coming week as part of the Microsoft 365 Copilot user subscription license (USL). Limits apply to these models, but they are designed to support broad day-to-day AI usage across organizations and are implemented in such a way that the vast majority of users are not expected to reach them. Users approaching a limit will receive in-product notifications and can continue their work by switching to Auto mode or selecting another available model. 

[Rollout Schedule:]

• General Availability:
• Cowork and Copilot Studio: Rollout begins today, September 30, 2026.
• Word, Excel, PowerPoint and Chat: Phased rollout begins in the coming week. 

[Impact on Your Organization:

Who is affected:

• Cowork and Copilot Studio: Users assigned a user subscription license (USL) with usage-based billing (UBB) enabled.
• Word, Excel, PowerPoint, and Chat: Users assigned a user subscription license (USL).
• Access to Claude Sonnet 5.5 additionally requires the Anthropic subprocessor to be enabled in your organization.
• Access to GPT-6.1 Sol in select surfaces requires the OpenAI subprocessor to be enabled. Learn more: OpenAI as a subprocessor in Microsoft Online Services | Microsoft Learn. 
• As a reminder, this setting controls only whether OpenAI models operated by OpenAI (provided by OpenAI as a subprocessor) can be used. OpenAI models operated by Microsoft (Azure OpenAI) aren’t affected and remain available in Copilot regardless of this setting.

Platforms/Services:

• (USL) Microsoft 365 Copilot Chat
• (USL) Microsoft Word
• (USL) Microsoft Excel
• (USL) Microsoft PowerPoint
• (UBB) Copilot Cowork
• (UBB) Microsoft Copilot Studio

What will happen:

• Users will be able to select GPT-6.1 Sol and Claude Sonnet 5.5 using the model selector from supported Microsoft Copilot experiences.
• The feature is enabled by default for eligible licensed users who meet the applicable configuration requirements.

[Action Required / Recommendations:]

No action is required for organizations that want users to access these models.

Recommended actions:

• Review whether the Anthropic subprocessor is enabled if you plan to make Claude Sonnet 5.5 available to users.
• Review whether the OpenAI subprocessor is enabled if you plan to make GPT-6.1 Sol broadly available to users. If disabled, GPT-6.1 Sol may not be available from all supported Copilot surfaces.
• Review your organization’s AI usage guidance and communicate model availability to end users.
• Inform helpdesk and support teams that users may encounter usage-limit notifications and can continue working using Auto mode or another available model.
• Review the announcement blog for additional details: Available today: OpenAI’s GPT-6.1 Sol and Claude Sonnet 5.5 in Microsoft Copilot | Microsoft Community Hub.
• Update internal user documentation and training materials, as appropriate.

[Compliance Considerations:]

Source: Microsoft Message Center • Analysed by MWPro

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