On March 18, 2026, GitHub announced GPT-5.3-Codex as the first long-term support model for Copilot Business and Enterprise, with a 12-month availability window.
Key ideas
- GitHub introduced GPT-5.3-Codex as Copilot's first LTS model for enterprise plans.
- The support window runs from February 5, 2026 to February 4, 2027.
- It will also become the default model for Copilot Business and Enterprise starting May 17, 2026.
What GitHub actually announced
According to the official changelog published on March 18, 2026, GitHub is introducing a long-term support commitment for selected models inside Copilot Business and Copilot Enterprise.
GPT-5.3-Codex is the first model to receive that treatment. GitHub says it launched on February 5, 2026 and will remain available until February 4, 2027 for those plans.
Why this matters
This is not just a model swap. It is a sign that AI tooling is being adapted to the realities of enterprise environments, where security reviews, procurement and internal approval processes move at a different pace.
When a company evaluates an AI assistant, stability matters almost as much as output quality. A clear availability window reduces operational uncertainty.
- More predictability for internal review processes.
- A clearer standard model for larger teams.
- A more serious enterprise story around Copilot adoption.
What changes next
GitHub also announced that GPT-5.3-Codex will replace GPT-4.1 as the default Copilot model for Business and Enterprise organizations within 60 days of the announcement.
The date GitHub gives for that change is May 17, 2026. This does not apply to Copilot Pro, Pro+ or Free.
