OpenAI names GPT 5.6 the ‘preferred model’ for Microsoft 365 Copilot amid partnership questions

Just days after reports reignited speculation about the future of OpenAI's partnership with Microsoft, the ChatGPT maker has announced that its latest flagship model, GPT 5.6, will serve as the "preferred model" for Microsoft 365 Copilot.

The announcement came alongside the launch of GPT 5.6 on Thursday, with OpenAI positioning the move as further evidence that its long-standing collaboration with Microsoft remains firmly in place despite growing industry chatter about the companies pursuing increasingly independent AI strategies.

OpenAI said GPT 5.6 will power Microsoft 365 Copilot across several of the software giant's productivity tools, including Word, Excel, PowerPoint and Cowork. The company described the rollout as part of its continued effort to bring advanced AI capabilities to businesses and individual users through Microsoft's ecosystem.

"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 said in a blog post announcing the update.

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OpenAI responds to growing speculation

The timing of the announcement is notable.

Earlier this week, Bloomberg reported that Microsoft had begun integrating more of its own in-house AI models into Microsoft 365 applications as part of a broader strategy to lower the costs associated with running generative AI services. According to the report, Microsoft's internally developed models, known as MAI, were increasingly being used in products such as Word and Excel.

The report fuelled fresh debate over whether the relationship between Microsoft and OpenAI was entering a new phase.

Microsoft has invested billions of dollars in OpenAI and has relied extensively on its models to power Copilot experiences across Windows, Microsoft 365 and Azure. At the same time, the company has been investing heavily in its own AI research, developing proprietary models that could reduce its dependence on external providers over time.

That evolving strategy has led many industry observers to question whether the two companies are gradually becoming more competitive than collaborative.

A partnership that continues to evolve

OpenAI's latest announcement appears intended to reassure customers that its technology will remain central to Microsoft's AI offerings.

However, the company stopped short of explaining what being the "preferred model" specifically entails. While the designation suggests GPT 5.6 will take priority within Microsoft 365 Copilot, OpenAI did not provide details on how workloads will be divided between its models and Microsoft's own AI systems.

Importantly, Bloomberg's earlier report did not suggest Microsoft was abandoning OpenAI's technology altogether. Instead, it indicated that the company was expanding the role of its internally developed models to improve efficiency and reduce operating costs.

As a result, OpenAI's latest statement does not necessarily contradict those reports. Rather, it signals that GPT 5.6 will continue to play a prominent role within Microsoft's AI-powered productivity suite even as Microsoft broadens its own portfolio of foundation models.

For customers, the announcement offers reassurance that one of OpenAI's most advanced models will remain deeply integrated into the Microsoft software they use every day. For the wider AI industry, it underscores a more nuanced reality: even as strategic partners build competing technologies, their commercial relationship can continue to evolve rather than come to an abrupt end.