OpenAI research: Codex now primary AI tool for all departments

The paper's central claim is that the unit of knowledge work is changing from single interactions to delegated, long-horizon tasks. The evidence comes from OpenAI's own internal usage, where Codex adoption grew in tandem with its capabilities. As Codex leveraged stronger models and new features, it became capable of taking on more tasks, and usage patterns shifted accordingly.

The data shows a clear progression: engineers at OpenAI first shifted the majority of their usage to Codex by December 2025, followed by Legal, Finance, and Recruiting around April 2026. Notably, non-technical departments made the transition much faster once they started. This pattern suggests that as agentic tools become more capable, they move beyond their initial developer audience into broader knowledge work, allowing workers to do adjacent tasks that previously required specialized technical support.

The stakes for businesses and workers hinge on whether this internal OpenAI experience reflects the broader market trajectory. The paper itself notes this is "likely to be what the future of work looks like," but the findings are based on frontier users with broad, low-friction access to the tool. The real test will be whether the adoption trends observed inside OpenAI generalize to external individual and organizational users, especially as the tools continue to improve and handle longer, more complex tasks.