Microsoft upgrades Microsoft 365 Copilot to GPT‑5.5 in May update

Microsoft has begun pushing GPT-5.5 models into Microsoft 365 Copilot, widening the use of newer OpenAI systems across its workplace AI products. A May 7 Microsoft 365 Copilot blog post said GPT-5.5 Instant was added to Microsoft 365 Copilot and Microsoft Copilot Studio and was starting to roll out to Copilot Chat experiences. An April 27 Microsoft post said GPT-5.5 Thinking — shown in product menus as GPT-5.5 Reasoning in some places — was also rolling out across Microsoft 365 Copilot in Copilot Chat, Word, Excel and PowerPoint. Microsoft’s own release notes show the broader Copilot service is still changing through May, with new chat features posted on May 19. ### So what, exactly, did Microsoft add? Microsoft said GPT-5.5 Instant is meant for “everyday work tasks” and is designed to produce more accurate, concise responses than GPT-5.3 Instant. The May 7 post said the model improves common work questions, image uploads and STEM-related tasks, while reducing unnecessary follow-up questions. In Copilot Chat, Microsoft said the model appears as “GPT-5.5 Quick response” in the model selector. (techcommunity.microsoft.com) An April 27 Microsoft post described GPT-5.5 Thinking as a separate upgrade aimed at deeper analysis, multi-step work and visual creation. Microsoft said that model was rolling out across Copilot Chat, Word, Excel and PowerPoint, alongside ChatGPT Images 2.0 in PowerPoint and, later, Copilot Chat. ### Where inside Microsoft 365 will users actually see it? (techcommunity.microsoft.com) Copilot Chat is the first clear landing place in Microsoft’s own posts. Microsoft said licensed Microsoft 365 Copilot users get priority access to GPT-5.5 Instant, while users without a Microsoft 365 Copilot license get standard access. For developers and agent builders, Microsoft said GPT-5.5 Instant is also rolling out in Copilot Studio early release cycle environments and is available in Microsoft Foundry. (techcommunity.microsoft.com) Microsoft’s release notes published May 19 did not headline GPT-5.5 again, but they show the surrounding Copilot workflow changes landing at the same time. Those notes said users can add Outlook emails and email text directly into Copilot Chat prompts and open PDFs inside Copilot Chat on Windows, Mac and the web, keeping document review inside the Copilot interface. ### Why are there different GPT-5.5 names? Microsoft is using different labels depending on the product surface. (techcommunity.microsoft.com) The May 7 Microsoft post called the faster model GPT-5.5 Instant and said users would see it as “GPT-5.5 Quick response” in Copilot Chat. The April 27 post said GPT-5.5 Thinking appears in Copilot Studio early release cycle environments as “GPT-5.5 Reasoning.” (learn.microsoft.com) That naming split matters because Microsoft is positioning the models for different kinds of work. Microsoft’s descriptions separate faster, shorter answers from deeper analysis and multi-step tasks, rather than presenting GPT-5.5 as one single mode everywhere. ### What is the risk for companies adopting it now? Info-Tech Research Group said this week that Microsoft 365 Copilot deployments can “create confusion, risk, and unrealized expectations” without a structured approach. (techcommunity.microsoft.com) The firm’s guidance said organizations need effective controls, capability-aligned use cases, clear guardrails and readiness planning if they want Copilot adoption to produce measurable value. Info-Tech said weak controls can create risk, while overly restrictive controls can limit value. (techcommunity.microsoft.com) Its framework calls for defined ownership, responsible AI principles and structured change management so adoption does not fragment across teams. ### What should readers watch next? Microsoft’s May 19 release notes say Copilot features are introduced through a “safe deployment model,” meaning updates first reach a subset of users inside a tenant before expanding more broadly. (infotech.com) That means GPT-5.5 availability can vary by license, app and release environment even after Microsoft announces it. Microsoft said GPT-5.5 Instant began rolling out on May 7 and GPT-5.5 Thinking was already expanding across Word, Excel and PowerPoint as of April 27. (infotech.com) The next concrete checkpoints are Microsoft 365 Copilot release notes and Microsoft 365 Copilot blog updates, where the company is posting feature-by-feature rollout details through May 2026. (techcommunity.microsoft.com) (learn.microsoft.com)