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Available today: OpenAI's GPT-6.1 Sol and Claude Sonnet 5.5 in Microsoft Copilot

Xia_Song's avatar
Xia_Song
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Sep 30, 2026

Earlier this month, Anthropic's Claude Opus 5.5 and OpenAI's GPT-6 Sol joined model choice in Microsoft Copilot. Now, we're continuing to expand that choice by bringing GPT-6.1 Sol and Claude Sonnet 5.5 to Microsoft Copilot, giving users more model options for how they delegate work to Copilot. As customers take on different kinds of work with Copilot, expanded model choice gives them more flexibility to choose the experience that best fits the task at hand.

With Work IQ, Copilot grounds it in your organization's files, meetings, chats and business data, within your existing permissions, so responses are informed by the context of your work.

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GPT 6.1 Sol and Claude Sonnet 5.5 begin rolling out today with usage-based billing in Copilot Cowork and 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 user subscription license (USL)--limits apply but are designed to enable broad everyday AI usage across the organization, with the vast majority of users not expected to reach them. Users are warned as they approach a limit, and they can switch to Auto to continue working or select another model.  Availability and usage may vary by license, access, and region.

For the latest availability updates, see  AI at Work Roadmap and Microsoft Copilot release notes.  For more on GPT-6.1 Sol, read OpenAI’s announcement and Anthropic’s announcement on Claude Sonnet 5.5.

Updated Sep 30, 2026
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3 Comments

  • Langfordc's avatar
    Langfordc
    Copper Contributor
    Oct 15, 2026

    What is Microsoft doing with the limitations around context window within co-pilot ? As using these LLM's directly allows you to use the full context window instead of been limited to 100K in Co-Pilot ? 

  • schafferc's avatar
    schafferc
    Copper Contributor
    Oct 06, 2026

    What are those limits mentioned in the article, that apply GPT 6.1 Sol and Claude Sonnet 5.5? As an admin I would like to know about those to provide proactive guidance and communication to my users.

    • grant_jenkins's avatar
      grant_jenkins
      Bronze Contributor
      Oct 23, 2026

      Completely agree. We've asked Microsoft about this several times, but so far haven't been able to get clear guidance on the actual usage limits.

      We're already seeing multiple users reach these limits, so this is no longer just a future consideration. Without documented limits, or even indicative guidance, we have no reliable information we can provide to users about what to expect or how they should manage their usage.

      Xia_Song​ Do you have any details on what the actual limits are?

      It's also worth noting that the usage guidance linked from this article still contains the information below. Given that users are already reaching these limits, this guidance likely needs to be updated, ideally with greater transparency around what the limits are and how they're applied.

      Reach usage limits in the USL (coming soon): Users receive in-product notifications as they approach an applicable limit. After reaching the limit, they have the option to continue with UBB by consuming Copilot Credits or, if applicable, reroute to Auto to continue their work.