OpenAI's GPT-5.6 becomes the preferred model in Microsoft 365 Copilot

Yesterday, OpenAI announced the public rollout of its GPT-5.6 model series, which includes GPT-5.6 Sol, GPT-5.6 Terra, and GPT-5.6 Luna. GPT-5.6 Sol is the flagship model, GPT-5.6 Terra offers a balance between performance and cost, and GPT-5.6 Luna is the smallest and most cost-efficient model in the series. As with several previous OpenAI model launches, Microsoft also announced day-one availability of the GPT-5.6 models in Microsoft 365 Copilot.

While OpenAI models have been powering Microsoft 365 Copilot since its launch, over the past 12 months, Microsoft started using Anthropic's models for several scenarios. In addition to making Anthropic's models available on the Microsoft 365 Copilot model selector, the Opus series models were made the default in certain scenarios that required more complex work inside Copilot Cowork and inside Office apps. This was because Anthropic's models were performing significantly better than OpenAI's models in knowledge-work scenarios for a few months.

With the GPT-5.5 launch, OpenAI caught up with Anthropic's models in terms of knowledge-work capabilities. Thanks to significant improvements and high cost-efficiency, Microsoft has now selected the new GPT-5.6 series models as the preferred models for Microsoft 365 Copilot. The GPT-5.6 family of models is available now in Microsoft 365 Copilot inside Word, Excel, PowerPoint, Chat, and Cowork. The company highlighted that it worked with OpenAI to optimize GPT-5.6 for knowledge work across Microsoft 365 apps.

Nitin Agrawal, President, Copilot & Agents Core, Microsoft, said the following regarding GPT-5.6 series availability inside Microsoft 365 Copilot:

“We can’t wait for customers to see what GPT‑5.6 in Microsoft 365 will do, enabling them to work even more effectively with AI in the tools they use every day. Using Copilot powered by OpenAI’s latest model, customers will be able to produce more polished outputs in Word, Excel, PowerPoint, Cowork, and Copilot Chat, whether they are drafting documents, analyzing data, creating presentations, or collaborating across teams. We’re excited to continue building with OpenAI to bring more powerful AI experiences to people and organizations around the world.”

Microsoft will also access these OpenAI models directly through the API to bring GPT-5.6 to Microsoft 365 customers. Once the rollout is complete, Microsoft 365 Copilot may automatically use GPT-5.6 depending on the task. If the model selector is available, users can also choose GPT-5.6 explicitly.