Microsoft Quietly Shifts Thousands of Office Prompts to In-House AI

Microsoft has begun using its own MAI artificial intelligence models rather than those of OpenAI and Anthropicto complete prompts in its spreadsheet and email applications, Excel and Outlook, Bloomberg reported Tuesday (July 7), citing unnamed sources.

While there have been previous reports that Microsoft plans to transition to its own AI models, the fact that the company’s MAI is now handling tens of thousands of prompts in those applications each week was not previously known, according to the report.

Reached by PYMNTS, Microsoft declined to comment on the report.

According to the Bloomberg report, the company is shifting to its own models to reduce its AI costs and to avoid being reliant on other AI labs.

The report cited previous Bloomberg reports in which the CEO of Microsoft AI, Mustafa Suleyman, said that the company aims to reduce its spending on Anthropic models by using its own and that within months, a Microsoft model will start performing transcriptions in the company’s videoconferencing app, Teams, and other products.

It was reported in March 2025 that Microsoft was testing AI models from other companies that could replace OpenAI’s models in Copilot and that the tech giant was also training artificial intelligence models that could compete directly with OpenAI’s.

At that time, Microsoft had completed training of a family of models that performed nearly as well as OpenAI’s leading models on commonly accepted benchmarks, per that report.

A Microsoft spokesperson told PYMNTS at the time: “As we’ve said, we are using a mix of models, which includes models from OpenAI as part of our partnership, as well as Microsoft AI and open-source models.”

It was reported in January that Microsoft was increasing its spending on Anthropic, that it had become one of Anthropic’s top customers and that it was on track to spend around $500 million per year to use Anthropic’s AI models in Microsoft products.

PYMNTS reported in April that during the most recent quarter, Microsoft delivered double-digit growth across its core segments, primarily fueled by massive demand for AI and cloud services. At the same time, the company has faced investor concerns over elevated capital spending.