OpenAI announced via its @ChatGPT account on September 15 that GPT-5.5 will be retired from ChatGPT, ChatGPT Work, and Codex across all plans on October 14, 2026. Everyday users will be moved to the new default automatically, but builders and Codex users who hardcoded the model need to migrate to GPT-5.6 Sol or GPT-6 Astra before the cutoff.

The retirement does not affect the API: API-key-authenticated calls keep working. GPT-5.5 only launched April 23, 2026, giving it a short six-month run in the main product surfaces.