Microsoft routes some Office AI prompts to in-house MAI models to cut costs

Microsoft is quietly beginning to swap OpenAI and Anthropic out for its own MAI models in specific Office features where cost or data residency favor it—starting with some Excel, Word and Outlook prompts. The company has stood up a 'MAI Superintelligence Team' to reduce reliance on third-party frontier providers, a strategic pivot made possible by a 2025 renegotiation of its OpenAI contract.

Mechanically, Microsoft is doing model routing: keep premium third-party models for hard queries, but send routine or cost-sensitive prompts to cheaper in-house MAI models running on its own Azure fleet. That both trims the token bill and keeps data inside Microsoft's stack.

The backdrop makes the cost obsession sharp: reports say Microsoft 365 Copilot adoption is under 4.5% after three years, with only about 1% of users using it weekly—despite price increases. If Copilot revenue is soft, cutting inference cost is the fastest path to margin. This fits a clear theme-of-the-week: cost revolt against frontier pricing, echoed by US firms adopting Chinese open models 60–90% cheaper and Vercel's Guillermo Rauch pushing model routing over single-lab lock-in. Competitively it's awkward for OpenAI, whose biggest distributor is now building alternatives. Watch how far MAI displacement spreads and whether quality complaints surface in Office.