Microsoft 365 Copilot adds GPT‑5.5 models

Microsoft’s May 2026 updates to Microsoft 365 Copilot were not a single launch. They arrived in stages across late April and early May, adding OpenAI’s GPT-5.5 models to different parts of the product and tying them to document work, chat, image tasks and research flows. Microsoft said GPT-5.5 Thinking started rolling out on April 27, while GPT-5.5 Instant began rolling out on May 7. Microsoft’s release notes then showed additional Copilot workflow changes on May 19, including Outlook email grounding and PDF handling inside Copilot Chat. If you are trying to understand the change, the clearest point is that Microsoft added more than one GPT-5.5 option. The company described GPT-5.5 Thinking as the model for deeper analysis and multi-step work, and GPT-5.5 Instant as the faster model for common work questions, image uploads and STEM-related tasks. Microsoft also tied the update to “model choice tuned for work,” rather than a single model replacing everything at once. (techcommunity.microsoft.com) ### So what exactly was added, and when? On April 27, Microsoft said GPT-5.5 Thinking and ChatGPT Images 2.0 were becoming available in Microsoft 365 Copilot. The company said GPT-5.5 Thinking was rolling out across Copilot Chat, Word, Excel and PowerPoint, and said the update was meant to improve deeper analysis, multi-step work and visual creation. (techcommunity.microsoft.com) On May 7, Microsoft said GPT-5.5 Instant was being added to Microsoft 365 Copilot and Microsoft Copilot Studio. In Copilot Chat, the company said the model appears in the selector as “GPT-5.5 Quick response.” Microsoft also said Copilot Studio early release cycle environments would show it as “GPT-5.5 Chat.” (techcommunity.microsoft.com) ### Why did Microsoft split GPT-5.5 into “Thinking” and “Instant”? Microsoft’s own descriptions drew the distinction. The April 27 post said GPT-5.5 Thinking was for “deeper analysis” and “multi-step work,” while the May 7 post said GPT-5.5 Instant was designed for “everyday work tasks” and lower-latency responses. The company said Instant improves image analysis, STEM-related tasks, response concision and reduces unnecessary follow-up questions. (techcommunity.microsoft.com) That means the update is as much about workload routing as raw model branding. Microsoft has been presenting Copilot as a system that uses different models for different jobs, and its Copilot product pages describe newer features such as Researcher, Copilot Chat, agents and notebooks as part of a broader work stack built around Work IQ and multi-model intelligence. That is Microsoft’s framing, not an independent performance test. (techcommunity.microsoft.com) ### Where do these models show up inside Microsoft 365 Copilot? Microsoft named several surfaces. GPT-5.5 Thinking is rolling out across Copilot Chat, Word, Excel and PowerPoint, according to the April 27 post. GPT-5.5 Instant is rolling out to Copilot Chat and Copilot Studio, and Microsoft said it is also available in Microsoft Foundry for developers building AI solutions. (microsoft.com) Microsoft’s broader Copilot pages also show where the company wants those models used: chat, enterprise search, agents, notebooks and content creation. The product page says notebooks can combine chats, files and meeting notes, while agents can automate tasks or act on a user’s behalf inside workflows connected to apps and company data. ### What changed on May 19 besides the model rollout? (techcommunity.microsoft.com) Microsoft’s May 19 release notes highlighted workflow features rather than a new model announcement. The company said users can add emails and selected email text from Outlook directly into Copilot Chat prompts, a feature it described as improving context-aware responses. The same release notes said PDFs can now open directly inside Microsoft 365 Copilot Chat instead of a separate viewer or browser tab. (microsoft.com) Those changes matter because they show how Microsoft is pairing model upgrades with narrower product changes around grounding and document handling. In practice, the GPT-5.5 additions sit alongside tools that keep users inside Copilot Chat while they pull in emails, PDFs and other work content. ### Who gets access first? Microsoft said on May 7 that licensed Microsoft 365 Copilot users would receive priority access to GPT-5.5 Instant, while users without a Microsoft 365 Copilot license would have standard access. (learn.microsoft.com) The company said the rollout began that day for Copilot Chat experiences. Microsoft also noted that Copilot features are introduced using a safe deployment model that starts with a subset of users within a tenant before expanding more broadly. Microsoft’s release notes page and roadmap remain the places to watch for the next changes. As of May 20, the roadmap still lists the May 7 GPT-5.5 Instant announcement, and the release notes page shows May 19 as the latest dated update block for Microsoft 365 Copilot. (microsoft.com) (techcommunity.microsoft.com)