OpenAI and Thrive Holdings have launched a self-improving AI system designed to draft tax returns with up to 97% accuracy, enhancing its performance through continuous use. The system, which ran a pilot program through Crete Professional Alliance, processed 7,000 tax returns, focusing on complex 1040 and 1041 filings. The AI, built on OpenAI's Codex technology, improves by learning from corrections made by human accountants, significantly boosting accuracy over a short period. The collaboration between OpenAI and Thrive Holdings is notable for its unique business arrangement, with OpenAI acquiring an equity stake in Thrive Holdings. This partnership, announced on May 27, 2026, resulted in Thrive Holdings owning the intellectual property and products developed, a rare setup in AI partnerships. The system has demonstrated significant efficiency gains, reducing preparation time by one-third and increasing throughput by 50%.