OpenAI says GPT 5.6 is Microsoft Copilot's preferred model
OpenAI says GPT 5.6 is the preferred model for Microsoft 365 Copilot, confirming its newest family of models will continue powering Microsoft's workplace apps even as Bloomberg reports suggest Microsoft is routing more Word and Excel prompts through in-house MAI software to reduce costs. The July 9 announcement arrives during renewed speculation about whether the once-tight partners are drifting apart.
During OpenAI's GPT 5.6 launch on Thursday, the company said the model would become the preferred engine behind Microsoft 365 Copilot across Word, Excel, PowerPoint, and Cowork. OpenAI stated in a blog post that the partnership has always been about bringing capable AI to productivity tools, and that it looked forward to building on that shared commitment.
Key Takeaways
- OpenAI launched GPT 5.6 on July 9, 2026, naming it the preferred model for Microsoft 365 Copilot.
- The move follows Bloomberg reporting that Microsoft has begun using its own MAI models for a portion of prompts in apps like Word and Excel.
- OpenAI says its models will keep powering Microsoft's productivity suite, but what "preferred model" means in practice remains unclear.
- The same day, OpenAI No. 2 executive Fidji Simo stepped down from her full-time role after a longer-than-expected medical leave.
- Neither announcement fully settles questions about whether Microsoft and OpenAI are growing apart.
Why is OpenAI saying GPT 5.6 is the preferred Copilot model now?
Earlier this week, Bloomberg reported that Microsoft was replacing some of OpenAI's software with its own in-house models as part of a cost-cutting strategy. Those MAI models were increasingly being used to power apps including Word and Excel, the outlet noted.
That reporting raised a familiar question: were Microsoft and OpenAI—once seemingly inseparable—starting to go their separate ways? OpenAI's Thursday announcement appeared aimed at pushing back on breakup chatter.
By designating GPT 5.6 as the preferred model for Copilot 365, OpenAI framed its latest release as the continued backbone of Microsoft's office software. For more context on how AI reshapes everyday tools, see our Future Tech & AI Wonders coverage.
Are Microsoft and OpenAI really drifting apart?
Not entirely—at least not according to OpenAI. The company said its new model family would keep supporting Microsoft's suite of workplace and productivity apps. As TechCrunch reported, it was never suggested ChatGPT's software would stop powering Microsoft products; rather, Microsoft was simply relying more on its own software to cut costs.
OpenAI's preferred-model disclosure does not appear to negate Bloomberg's earlier reporting. Both can be true: GPT 5.6 may lead Copilot while Microsoft simultaneously routes some prompts to cheaper in-house alternatives.
What does 'preferred model' mean for Microsoft 365 users?
OpenAI did not fully define the term. TechCrunch noted that, beyond confirming OpenAI software would continue powering Microsoft's apps, the practical implications for customers remain fuzzy.
GPT 5.6 is meant to support users across Word, Excel, PowerPoint, and Cowork—the same productivity pillars where Microsoft has reportedly tested MAI models. The mix of models behind the scenes could vary even as OpenAI's release takes top billing.
For enterprise buyers weighing AI vendor relationships, the label signals continuity more than exclusivity. Microsoft is leaning on its own MAI models while still showcasing OpenAI's flagship release.
What else shook OpenAI leadership on the same day?
While OpenAI promoted GPT 5.6, the company also faced internal turbulence. Fidji Simo, OpenAI's No. 2 executive, stepped down from her full-time role after her medical leave proved longer than expected, TechCrunch reported.
Simo said she would transition to a part-time advisory position, citing a relapse of a neuroimmune condition she first disclosed in April. Her departure creates a leadership vacuum at a firm widely seen as preparing for a possible IPO—separate from the Microsoft partnership story, but part of a busy news cycle for the ChatGPT maker.