GPT-5 becomes the default Copilot model [MC1176368]

Message ID: MC1176368

[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 late October 2025 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:
  • Phase 1 (web, desktop): GPT-5 toggle is enabled by default. Users can choose to disable GPT-5 via the toggle and revert to previous models.
  • Phase 2 (web, desktop, mobile): GPT-5 becomes the default model. Users will no longer be able to opt out, and the GPT-5 toggle button will be removed.
  • 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.

Source: Microsoft

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