Products

GitHub Makes GPT-5.3-Codex the Default Base Model for All Copilot Business and Enterprise Organizations

On May 17, 2026, GitHub announced that GPT-5.3-Codex is now the base model for all Copilot Business and Copilot Enterprise organizations, replacing GPT-4.1. The change applies organization-wide unless other models are explicitly approved, and GPT-5.3-Codex is designated as OpenAI's first long-term support (LTS) model, guaranteed available through February 4, 2027.

Tech Insights Reporter May 17, 2026 5 min read San Francisco, CA

TLDR

GitHub updated its Copilot offerings on May 17, 2026, making GPT-5.3-Codex the default base model for every Copilot Business and Copilot Enterprise organization. This replaces the previous GPT-4.1 base and applies automatically unless an organization has approved alternative models through its internal review process. GPT-5.3-Codex is also OpenAI's first LTS model, ensuring availability for a full 12 months from its February 5, 2026 launch date through February 4, 2027.

Details of the Change

The base model is the default used when organizations have not yet approved other models. This update standardizes access to the newer GPT-5.3-Codex across business and enterprise plans.

Key timeline from the announcement:

March 18, 2026: LTS and base model changes announced.
May 17, 2026: GPT-5.3-Codex becomes the base model for all Copilot Business and Copilot Enterprise organizations.
February 4, 2027: End of support for the model in these plans.

The change aims to provide enterprises with the stability of an LTS model while incorporating newer capabilities from GPT-5.3-Codex.

Context and Implications

This follows OpenAI's broader model releases and GitHub's integration of advanced coding models into Copilot. Organizations using Copilot for business or enterprise can still opt into other approved models, but the default shifts to the newer Codex variant for improved performance in coding and related tasks.

Why this story matters

Making a frontier coding model the default base across millions of enterprise users accelerates adoption of advanced AI-assisted development while introducing LTS guarantees that address enterprise needs for predictability and security review cycles. It marks a maturation in how AI coding tools are deployed at scale in corporate environments.

Sources

GitHub changelog: "GPT-5.3-Codex is now the base model for Copilot Business and Enterprise" (github.blog/changelog/2026-05-17-gpt-5-3-codex-is-now-the-base-model-for-copilot-business-and-enterprise/, published May 17, 2026). Primary source with exact rollout details, timeline, and LTS designation.
Related OpenAI model announcements referenced in the changelog for context on GPT-5.3-Codex launch.

Featured Image Alt Text

GitHub Copilot logo with GPT-5.3-Codex branding, showing code completion interface and LTS badge for enterprise stability.