AI beats licensed accountants on speed and accuracy, but still can't close the books without supervision

AI models are faster, more accurate and far cheaper than licensed accountants at structured bookkeeping tasks, according to a study by Mercor. In the experiment, twelve licensed CPAs with an average of five and a half years of experience worked through simplified tasks from the APEX Accounting Benchmark.

Eighteen months ago, the best models still scored below the accountants' average of about 37 percent. Today they solve the same tasks almost flawlessly.

The full benchmark tells a harder story

The complete APEX Accounting benchmark is much larger: 160 tasks across 10 simulated companies, built by more than 40 professionals who average eleven years of experience. Claude Opus 5.5 currently leads with 61.8 percent of grading criteria met, followed by Fable 5.1 at 61.0 percent and GPT-6 Astra at 57.9 percent.

At the same time, no model fully solved almost 60 percent of the tasks. According to Mercor, AI still can't close the books without oversight.

What the study leaves out

Mercor also admits that its tasks test exactly what AI does best: hunting down details and following instructions precisely. The study left out key parts of the job, such as talking with clients, checking in with colleagues and drawing on context built up over years.

That is why accountants can't be replaced, the company says, though it expects major productivity gains across the industry.