OpenAI GPT-5.6 becomes preferred model for Microsoft 365 Copilot amid partnership questions

OpenAI says GPT 5.6 is the 'preferred model' for Microsoft Copilot amid breakup chatter

Earlier this week, Bloomberg reported that Microsoft was replacing some of OpenAI's software with its own in-house models in an effort to cut costs. Those in-house models, known as MAI, were increasingly being used to power apps like Word and Excel, the outlet noted. The story raised an increasingly common question about the two companies, which were once seemingly inseparable, and have recently sent mixed signals about the status of their situationship: Were the two companies drifting apart? Now, OpenAI is attempting to put any insinuations of such a break to rest. During OpenAI's launch of GPT 5.6 on Thursday, the company announced that it would become the "preferred model" powering Microsoft's 365 Copilot. OpenAI noted in a blog post published Thursday that GPT 5.6 would support Microsoft users across the company's suite of productivity apps, including Word, Excel, PowerPoint, and Cowork. "Our partnership with Microsoft has always been about bringing the benefits of advanced AI to more individuals and organizations, and we're excited to continue building on that shared commitment," OpenAI wrote in a blog post. What being a "preferred model" actually means isn't entirely clear, other than that OpenAI's software will continue to power Microsoft's apps. That said, it was never reported that ChatGPT's software would stop powering Microsoft's apps -- merely that Microsoft was relying increasingly on its own software in an effort to reduce costs. The new "preferred model" disclosure doesn't appear to negate that previous reporting.

OpenAI GPT-5.6 is now the preferred model for Microsoft 365 Copilot

OpenAI named GPT-5.6 the preferred model powering Microsoft $MSFT 365 Copilot on Thursday, bringing the model family into Word, Excel, PowerPoint, Copilot Chat, and a collaborative feature called Cowork. Microsoft said the two companies partnered to optimize GPT-5.6 for knowledge work across the productivity suite. GPT-5.6 is a family of three models -- Sol, Terra, and Luna -- covering flagship, enterprise, and high-volume use cases, the company said. Microsoft will access the models both natively and through the OpenAI API. In Word, the updated Copilot is designed to turn rough ideas into more complete drafts with fewer rounds of prompting, according to Microsoft's technical blog. In Excel, it is meant to support more complex analysis with less manual assembly. In PowerPoint, Copilot can generate richer presentation drafts with stronger visual balance. In Cowork, the model is built to carry multi-step tasks from an initial instruction through to a finished result, rather than returning a draft or recommendation for the user to complete. Users may see GPT-5.6 selected by Copilot when the system determines it fits the task, or they can choose it from a model selector where that option is available. Availability may vary by region and tenant configuration, Microsoft said. "Microsoft 365 is where millions of people write, analyze, create, and collaborate every day," said Nikunj Handa, head of API product at OpenAI, in a statement. "By bringing GPT-5.6 to Microsoft 365 Copilot through the OpenAI API, we're helping organizations get more useful work from every token, and more value from AI in the tools they already use." The announcement arrived as the Microsoft-OpenAI relationship has drawn attention over questions about the direction of their partnership. A Bloomberg report earlier this week described Microsoft shifting toward its own MAI models for apps such as Word and Excel -- a cost-reduction move that, according to TechCrunch, renewed scrutiny of how central OpenAI's technology remains to Microsoft's product stack. Microsoft has been building out its MAI model family, which spans coding, image generation, transcription, and voice, and has publicly framed the effort as a push for long-term self-sufficiency. The company has also used Anthropic models in certain Microsoft 365 Copilot tasks after internal testing, and it hosts models from Meta $META, Mistral, and other providers in its data centers. As TechCrunch observed, labeling GPT-5.6 the preferred model leaves room for both things to be true simultaneously: OpenAI's software can hold that designation while Microsoft continues building out its own AI capabilities to manage costs. GPT-5.6 received broad U.S. regulatory clearance earlier this week after the Commerce Department's Center for AI Standards and Innovation completed an evaluation of the model, ending a period of restricted access that had confined it to a small number of government-vetted partners.