MC1176368: GPT-5 becomes the default Copilot model

Summary

• Microsoft 365 Copilot will use GPT-5 as the default model, enhancing user experience with faster and more accurate responses.
• The rollout occurs in two phases, with a toggle for GPT-5 in Phase 1 and mandatory use in Phase 2.
• Users can bypass GPT-5 reasoning for direct responses by selecting “Get a quick answer.”
• All users with Microsoft 365 Copilot licenses across web, desktop, and mobile will be affected by this change.
• No admin action is needed, but communication and updates to internal documentation are advised.

Admin Impact: Low
User Impact: Medium
Release Start: 01 Oct 2025
Release End: 30 Nov 2025
Services: M365 Copilot
Category: Plan for change
Tags: New Feature, User Adoption

History

10/20/2025 Item Added to Message Center

Microsoft Message

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.