Microsoft's $2B Anthropic bill shows Copilot's fix has a price

Microsoft is spending heavily to stop Copilot losing customers to its own reputation, and Anthropic is collecting the cheque. According to The Information's report, Microsoft is on track to pay Anthropic more than $2 billion a year for models that power Copilot. The report cites a single source, and neither company has confirmed the number.

The figure marks a steep rise. An earlier The Information report, in early 2026, put Microsoft's Anthropic spending at about $500 million a year. Microsoft is now blending Claude with OpenAI models across Word, Excel, Outlook and PowerPoint, according to the report, as summarised by AI Weekly.

The reported driver is product quality. Customer complaints, as summarised in the report, held that Copilot was "buggy and not good enough at automating work in Excel or PowerPoint." Anthropic's newer models reportedly performed better on advanced Excel financial functions and on generating PowerPoint decks from instructions.

The internal push came from Charles Lamanna, Microsoft's new Office chief. He reportedly urged CEO Satya Nadella to pay for Anthropic models despite the higher cost. Several senior executives reportedly name Lamanna as a potential successor to Nadella.

Key details are missing. The report doesn't say whether Microsoft is buying API inference, dedicated capacity or a longer-term commitment. It also doesn't say who absorbs the cost gap between Anthropic and OpenAI models.

For Anthropic, a customer of this size, if the number holds, makes Microsoft one of its largest revenue sources and gives it a foothold inside the most widely used office software. The fourfold jump from the early-2026 estimate suggests Claude has moved from a supplement to a core part of Copilot's workload.

OpenAI is the exposed party. Microsoft is keeping its models in the mix, but it is paying a premium elsewhere because it judged the output better for Excel and PowerPoint work. Watch the unanswered questions: the contract structure will show how locked in Microsoft is, and the cost split will show whether Copilot margins or customer pricing absorb the bill. Until a second source confirms the figure, treat $2 billion as a strong signal rather than a settled number.