# Microsoft Shifts Office Prompts to In-House AI

> Source: <https://letsdatascience.com/news/microsoft-shifts-office-prompts-to-in-house-ai-1224d03c>
> Published: 2026-07-07 19:23:57+00:00

**Microsoft** has begun routing some **Excel** and **Outlook** AI prompts to its internal `MAI` models, according to PYMNTS and other Bloomberg-derived coverage published on July 7. The reports say the in-house models are handling **tens of thousands** of prompts per week across those Office apps, while Microsoft declined to comment to PYMNTS and the exact workload share remains small and unspecified. For practitioners, the signal is that high-volume AI product features may increasingly use routing layers that send routine requests to cheaper internal models and reserve external frontier models for harder tasks. That shift raises practical work around regression testing, latency budgets, telemetry, user disclosure, and cost-per-inference monitoring whenever model providers change behind a familiar product surface.