Building self-improving tax agents with Codex

Tax AI is a system built by OpenAI and Thrive Holdings that uses Codex (a code-generating AI model) to automate tax return preparation for accounting firms, and it improves itself automatically rather than waiting for engineers to manually fix problems. The system learns from real-world use by collecting practitioner feedback, tracking how returns are processed (production traces, or a structured record of inputs and outputs), and using tailored evaluations to continuously refine itself. Within six weeks of launch, the system improved from only 25% of returns being correct enough to need minimal fixes to 86% reaching that standard.