Summary:
GPT-5 is now the default model for Microsoft 365 Copilot, with three reasoning modes: Auto, Quick response, and Think deeper.
Users can select their preferred mode, and their choice will be remembered for future chats.
A new selector will appear in Copilot experiences, enabling mode changes without admin intervention.
The feature is enabled by default for all users, with no required actions for administrators or users.
Admin Impact
Low
User Impact
Low
Release Start
04 Dec 2025
Release End
08 Dec 2025
Services
M365 Copilot Chat
Category: Plan for change
Tags
New Feature
User Adoption
Admin Action
History
Date Description
12/4/2025 Item Added to Message Center
Microsoft Message
As announced in MC1176368 (October ’25) GPT-5 is now the default model and today we’re introducing the ability for your users to select how much reasoning to apply.
Users can choose from three modes:
Auto (default): Copilot decides how long to think.
Quick response (chat): Copilot answers right away.
Think deeper (reasoning): Copilot thinks longer for better answers.
This change is associated with Microsoft 365 Roadmap ID: 532736
When this will happen:
General Availability (Worldwide): Rollout will begin December 4, 2025, and we expect to complete by December 8, 2025.
How this affects your organization:
Who is affected: All users of Microsoft 365 Copilot.
What will happen:
Users will see a new selector in Copilot experiences.
Default mode is Auto; users can switch to Quick response or Think deeper.
User’s choice is remembered and retained for new chats.
No admin configuration changes required. There are no admin controls for this feature.
Feature is enabled by default for all tenants.
What you can do to prepare:
No action required; this is a standard rollout.
Optional: Communicate the new modes to helpdesk staff and users.
Compliance considerations:
No compliance impacts identified. Review your organization’s policies as needed.