GPT-5.3-Codex Becomes Default for GitHub Copilot Business/Enterprise — First LTS Model with 12-Month Availability Guarantee

GitHub Blog·medium signal

As of May 17, GPT-5.3-Codex is the base model for all Copilot Business and Enterprise organizations, replacing GPT-4.1. It's GitHub's first long-term support (LTS) model, guaranteed available through February 4, 2027, giving enterprises stability for internal security and compliance reviews. GitHub data shows GPT-5.3-Codex has a 'significantly high code survival rate' among enterprise customers. Separately, GitHub removed all Gemini models and GPT-5.2 Codex from Copilot Chat on the web (May 20), narrowing the model selection.