Microsoft 365 Copilot now runs on OpenAI's GPT-5.6, the companies announced on July 9, 2026, boosting AI capabilities in Word, Excel, PowerPoint, and the collaborative workspace Cowork. GPT-5.6, OpenAI’s latest model family, launched publicly the same day after a delayed rollout due to U.S. cybersecurity reviews, replacing GPT-4 which debuted in March 2023. According to OpenAI, the model is optimized to produce higher-quality outputs per token, offering stronger performance at a lower cost. Users can expect faster drafting and editing in Word, more efficient data analysis in Excel, automated creation of visually refined presentations in PowerPoint, and streamlined collaboration in Cowork. “With GPT-5.6 powering Copilot, customers can create polished outputs across Microsoft 365 tools with less effort,” said Nitin Agrawal, President of Copilot & Agents Core at Microsoft. The integration relies on OpenAI’s API and reflects the ongoing partnership to embed advanced AI into enterprise software. Its flagship variant, GPT-5.6 Sol, is tailored for complex workloads. Public availability followed a restricted preview phase in late June 2026 after compliance with U.S. government cybersecurity protocols.