MC1176368 – M365 Change Digest

One-line summary

Microsoft 365 Copilot will use GPT-5 as the default model in a phased rollout starting early November 2025; users lose opt-out after Phase 2, affecting all Copilot endpoints.

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Details

Summary

GPT-5 will become the default Microsoft 365 Copilot model in a phased rollout from early to late November 2025. Initially, users can toggle GPT-5 on or off; later, it becomes mandatory with no opt-out. GPT-5 offers faster, more accurate responses with dynamic model routing and deeper reasoning.

Body (from Message Center)

Updated October 30, 2025: We have updated the timeline. Thank you for your patience.

[Introduction]

We’re updating the default experience for users with the Microsoft 365 Copilot license by introducing GPT-5 as the standard model. GPT-5 is OpenAI’s most advanced language model, designed to deliver faster, more accurate, and more context-aware responses. It features dynamic model routing, which automatically selects the best-performing variant for each prompt—using high-throughput models for quick replies and deeper reasoning models for complex tasks. This change simplifies the user experience and enhances performance across all Copilot endpoints.

[When this will happen:]

General Availability (Worldwide): Phased rollout begins early November 2025 (previously late October) and completes by late November 2025.

[How this affects your organization:]

Who is affected: All users with a Microsoft 365 Copilot license across web, desktop, and mobile experiences.
What will happen:
- The rollout will occur in two phases:
- The GPT-5 default experience will also apply to Copilot Chat in the Microsoft 365 apps. The exception is on Teams mobile, which is planned to rollout beginning late November 2025.
- Copilot will automatically trigger GPT-5 reasoning based on prompt complexity.
  - Users will be able to bypass GPT-5 reasoning and get a direct response by selecting "Get a quick answer."

[What you can do to prepare:]

No admin action is required to enable this feature.
Communicate the phased rollout to helpdesk and support teams.
Update internal documentation to reflect the default use of GPT-5 and how to bypass reasoning if desired.
Review any training materials or user guides that reference the GPT-5 toggle.

[Compliance considerations]

Compliance Area	Explanation
Introduces or modifies AI/ML capabilities	GPT-5 introduces enhanced model routing and deeper reasoning capabilities that interact with user data.
Provides new ways of interacting with generative AI	Users will now interact with GPT-5 by default, without manual model selection.
Includes admin control	Admins can monitor usage via existing Copilot reporting tools but cannot disable GPT-5 as default after Phase 2.
Allows a user to enable and disable the feature themselves	Users can use the toggle to opt out of GPT-5 during Phase 1; Users cannot opt out during Phase 2, but they can bypass GPT-5 reasoning to get a direct response.

Raw JSON (for debugging)

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  "snapshot_item": {
    "action_required_by": null,
    "ai_action_required_by": null,
    "ai_actions": [
      "Communicate rollout to helpdesk/support",
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    ],
    "ai_master_tags": [],
    "ai_model": "gpt-4.1",
    "ai_summary": "Microsoft 365 Copilot will use GPT-5 as the default model in a phased rollout starting early November 2025; users lose opt-out after Phase 2, affecting all Copilot endpoints.",
    "ai_topics": [
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      "Teams",
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    ],
    "category": "planForChange",
    "details_map": {
      "Summary": "GPT-5 will become the default Microsoft 365 Copilot model in a phased rollout from early to late November 2025. Initially, users can toggle GPT-5 on or off; later, it becomes mandatory with no opt-out. GPT-5 offers faster, more accurate responses with dynamic model routing and deeper reasoning."
    },
    "id": "MC1176368",
    "importance": 5,
    "is_major_change": false,
    "last_modified": "2025-10-30T19:35:10Z",
    "ms_products": [
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    ],
    "platforms": null,
    "roadmap_ids": [],
    "services": [
      "Microsoft Copilot (Microsoft 365)"
    ],
    "severity": "normal",
    "tags": [
      "Updated message",
      "New feature",
      "User impact"
    ],
    "title": "(Updated) GPT-5 becomes the default Copilot model"
  }
}