Leaked documents shed light on how much OpenAI is paying Microsoft

After a year of frenetic deals and rumors of an upcoming IPO, financial scrutiny of OpenAI is intensifying. Leaked documents obtained by technology blogger Ed Zitron provide more of a glimpse into OpenAI’s financials — specifically its revenue and computing costs over the past two years.

Zitron reported this week that in 2024, Microsoft received $493.8 million in revenue share payments from OpenAI. In the first three quarters of 2025, this number jumped to $865.8 million, according to the documents he reviewed.

OpenAI is said to share 20% of its revenue with Microsoft as part of an earlier deal in which the software giant invested more than $13 billion in the powerful AI startup. (Neither the startup nor the folks at Redmond have publicly confirmed that percentage.)

However, this is where things get a little tricky, because Microsoft also shares revenue with OpenAI behind About 20% of Bing and Azure OpenAI Service revenue, a source familiar with the matter told TechCrunch. Bing is powered by OpenAI, and the OpenAI service sells cloud access to OpenAI models to developers and businesses.

The source also told TechCrunch that the leaked payments refer to Microsoft’s net revenue share, not its total revenue share. In other words, it doesn’t include what Microsoft paid to OpenAI from Bing and Azure OpenAI revenues. Microsoft deducts these numbers from its internally reported revenue share numbers, according to this person.

Microsoft doesn’t disclose how much it makes from Bing and Azure OpenAI in its financial statements, so it’s difficult to estimate how much the tech giant earns.

However, the leaked documents provide a window into the most popular company in private markets today — not just how much revenue it generates, but also how much it spends relative to those revenues.

So, based on the widely reported 20% revenue share statistic, we can conclude that OpenAI’s revenue will be at least $2.5 billion in 2024 and $4.33 billion in the first three quarters of 2025 – but it’s very likely more than that. Previous reports from The Information estimated OpenAI’s revenues for 2024 at about $4 billion, and its revenues from the first half of 2025 at about $4.3 billion.

Altman recently said that OpenAI’s revenue is “significantly more” than the reported $13 billion annually, that it will end the year above the $20 billion annual revenue run rate (which is a prediction, not guidance on actual revenue), and that the company could reach $100 billion by 2027.

According to Zitron’s analysis, OpenAI may have spent approximately $3.8 billion on inference in 2024. This spending has increased to approximately $8.65 billion in the first nine months of 2025. Inference is the computing used to run an AI model trained to generate responses.

OpenAI has historically relied almost exclusively on Microsoft Azure to provide compute access, though it has also struck deals with CoreWeave, Oracle, and, more recently, AWS and Google Cloud.

Previous reports have estimated OpenAI’s total computing spending at $5.6 billion for 2024 and its “cost of revenue” at $2.5 billion for the first half of 2025.

A source familiar with the matter told TechCrunch that while OpenAI’s spending on training is mostly non-cash — meaning it’s paid for from credits Microsoft gave OpenAI as part of its investment — the company’s inference spending is largely cash. (Training refers to the computing resources needed to initially train the model.)

Although it’s not a complete picture, these numbers suggest that OpenAI could spend more on inference costs than it generates in revenue.

These implications promise to add to the incessant chatter about artificial intelligence that has seeped into every conversation from New York City to Silicon Valley. If modeling giant OpenAI is still in the red running its models, what might this mean for huge investments in staggering valuations for the rest of the AI ​​world?

OpenAI declined to comment. Microsoft did not respond to TechCrunch’s request for comment.

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