OpenAI Reaffirms Role in Microsoft 365 Copilot as GPT 5.6 Amid Cost-Cutting Signals

OpenAI moved to reassure observers about the health of its partnership with Microsoft by announcing that its latest GPT 5.6 model will serve as the "preferred model" powering Microsoft 365 Copilot. The declaration came as the tech pair face intensifying speculation about the durability of their relationship.

The Cost-Cutting Context#

Last week, Bloomberg reported that Microsoft had begun replacing certain OpenAI capabilities with its own internally developed AI models—known as MAI—to reduce expenses. The shift was particularly evident in Microsoft's core applications like Word and Excel, where the company leaned more heavily on homegrown technology. This move sparked questions about whether the two former partners were quietly distancing themselves from one another.

OpenAI's Counter-Move#

In unveiling GPT 5.6 on Thursday, OpenAI sought to counter that narrative by announcing the model would power Microsoft's full productivity ecosystem across 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," the company said in a statement.

What "Preferred" Actually Means#

The term "preferred model" remains somewhat ambiguous—OpenAI's clarification largely amounts to reaffirming that its software will remain integrated into Microsoft's applications. Importantly, nothing in the announcement directly contradicts the earlier reporting about Microsoft's parallel shift toward its own models; both developments can coexist. The companies may simultaneously rely more on internal tools for cost control while maintaining OpenAI as a key supplier for certain workloads.