Microsoft has begun replacing OpenAI and Anthropic models with its own "MAI" models in some AI features of Microsoft 365 apps such as Excel and Outlook, in a move said to be aimed at cutting AI operating costs.
July 7, 2026 · Microsoft AI
Microsoft swaps OpenAI & Anthropic for its own MAI models in Excel and Outlook
A quiet, unannounced shift now routes tens of thousands of Copilot prompts each week through Microsoft's in-house models — a bid to cut inference costs and reduce reliance on external AI partners.
10,000s
prompts/week in Excel & Outlook now run on MAI
7
MAI models unveiled at Build, June 2026
~1/3
MAI-Code-1-Flash output price vs GPT-4o
Coding cost, drawn to scale
Output-token price per million tokens — each block ≈ $0.75
~$13.50
GPT-4o
The MAI model family
MAI-Thinking-1
Reasoning · 35B active, 128K context — the model used in Office
MAI-Code-1-Flash
Coding · 5B active, lightweight agentic model
MAI-Image-2.5
Image gen/edit · beats Google Nano Banana Pro on Arena
MAI-Transcribe-1.5
Speech · 43 languages, 5× faster than prior
MAI-Voice-2
Voice generation · 15 languages
The case for
Handle routine tasks in-house, reserve frontier models for premium use. MAI-Thinking-1 is said to beat Claude Sonnet 4.6 in blind evaluations and match Claude Opus 4.6 on SWE-Bench Pro — while third-party token costs grow unsustainable.
The concern
An independent review called the MAI models "surprisingly mediocre" — usable for everyday work but not at the frontier. Users worry about being quietly moved to a weaker model at the same Copilot price.
Suleyman's stated goal: reduce — and ultimately eliminate — large payments to Anthropic.
• Trained from scratch on licensed data, no distillation• Copilot still lets users mix Anthropic, OpenAI & MAI in Auto or manual mode• No confirmed stumbles yet — real-world evaluation will decide the outcome
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