When is GPT-5.5 being retired?

OpenAI's official @ChatGPT account announced on September 15, 2026 that GPT-5.5 will be retired on October 14, 2026 from ChatGPT, ChatGPT Work and Codex, across all plans. That is less than six months after GPT-5.5 launched on April 23, 2026. The notice names only those product surfaces; the GPT-5.5 API is not affected by this announcement and OpenAI has published no API deprecation date for it as of September 22, 2026.

What should I use instead of GPT-5.5?

OpenAI's notice tells Codex users to switch to GPT-5.6 Sol or GPT-6 Astra. GPT-5.6 Sol is the like-for-like replacement: a mid-tier model at $4 per million input tokens and $20 per million output tokens (cut from $5/$30 on August 21, 2026), cheaper than GPT-5.5's $5/$30, with stronger coding scores. GPT-6 Astra, launched September 3, 2026 at $10/$50, is OpenAI's flagship with a 1,050,000-token context and 60% on Terminal-Bench 4.0; pick it for long agentic tasks. In ChatGPT, conversations that used GPT-5.5 move to the default model for your plan.

Does the GPT-5.5 retirement affect the API?

No. The September 15, 2026 notice covers ChatGPT, ChatGPT Work and Codex only. Developers calling gpt-5.5 through the OpenAI API or using their own API key in Codex CLI keep access, and OpenAI has not announced an API deprecation. Treat that as a reprieve, not a guarantee: OpenAI retired GPT-4.5 from the API on June 27, 2026 and o3 on August 26, 2026 with a few months' notice each time, so plan an API migration to GPT-5.6 Sol or GPT-6 Astra on your own schedule.

Will my ChatGPT conversations and Codex workflows migrate automatically?

OpenAI has not said so. The notice gives a date and replacement guidance for Codex; it does not promise automatic migration of saved prompts, custom instructions, Codex sessions, workspace defaults or tool configurations, nor behavioural, pricing or usage-limit parity between GPT-5.5 and its replacements. Inventory every place GPT-5.5 is selected — saved prompts, team instructions, runbooks, eval sheets — switch each to GPT-5.6 Sol or GPT-6 Astra, and test representative tasks before October 14, 2026.

Quick Answer

GPT-5.5 Retires October 14, 2026: What to Use Instead

Published: September 22, 2026

The short answer

GPT-5.5 disappears from ChatGPT, ChatGPT Work and Codex on October 14, 2026. OpenAI’s ChatGPT account posted the notice on September 15. The API is not part of it. If you pick GPT-5.5 anywhere in those three products today, replace it with GPT-5.6 Sol (cheaper, like-for-like) or GPT-6 Astra (flagship, long-horizon agents) before the date, and test — OpenAI has promised no automatic migration and no behavioural parity.

What the notice says — and doesn’t

Confirmed (September 15, 2026 notice)	Not confirmed
Retirement date: October 14, 2026	Any API retirement date for `gpt-5.5`
Surfaces: ChatGPT, ChatGPT Work, Codex	Automatic migration of conversations, saved prompts, Codex sessions
Scope: all plans — Free, Plus, Pro, Business, Enterprise, Edu	Behavioural parity between GPT-5.5 and replacements
Codex guidance: switch to GPT-5.6 Sol or GPT-6 Astra	Same usage limits or credit consumption on replacements

GPT-5.5 (“Spud”) launched on April 23, 2026 — the first frontier launch in two years to raise price per token, to $5/$30 — so it is being retired from consumer surfaces after less than six months. That cadence now matches OpenAI’s pattern: GPT-4.5 left on June 27, 2026 and o3 on August 26, 2026.

Your replacement options

	GPT-5.6 Sol	GPT-6 Astra	(retiring) GPT-5.5
Role	Mid-tier, OpenAI’s named like-for-like	Flagship	Mid/high tier
API price per MTok	$4 / $20 (cut Aug 21, 2026; was $5/$30)	$10 / $50; cached $1; ~2x above 272K	$5 / $30
Context	Large	1,050,000 tokens	Smaller than Astra
Terminal-Bench 4.0 (Artificial Analysis)	37.3% (xAI table, Max)	60%	—
DeepSWE v1.1	72.7%	—	—
Availability in ChatGPT	Plus and up; Luna is free-tier default	Plus/Pro/Work after enterprise Trusted Access	Until Oct 14
Codex	Yes	Yes	Until Oct 14

Choose GPT-5.6 Sol if your GPT-5.5 use was everyday chat, drafting, analysis or short coding tasks. It is cheaper than GPT-5.5 was, scores higher on software-engineering benchmarks, and is the model OpenAI itself names first. One caution: the $4/$20 price was reported as promotional (~3 months from August 21), so budget at $5/$30.

Choose GPT-6 Astra if you ran GPT-5.5 for multi-hour agentic coding or research. Astra’s 60% on Terminal-Bench 4.0 is the highest independently measured score of any model as of September 2026, and it emits few tokens per task, so its per-task cost is often close to Sol’s despite the 2.5x rate card. Details: What is GPT-6 Astra? and GPT-6 Astra vs Claude Fable 5.1.

Free-tier users already default to GPT-5.6 Luna (since August 2026); nothing to do.

Migration checklist (do it before October 14)

Inventory. Search saved prompts, custom GPTs, ChatGPT Work project instructions, Codex configs, team runbooks, eval spreadsheets and screenshots in training material for “GPT-5.5”. Admins: check workspace default-model settings.
Pick per workflow, not globally. Sol for chat/drafting/short code; Astra for long agents. Mixed teams will end up with both.
Set the model explicitly. ChatGPT retired automatic thinking escalation for Plus and Pro; you now choose model and reasoning effort in the picker, so a GPT-5.5 habit does not silently map to the right effort level on Sol or Astra.
Re-run representative tasks. Compare output format, tool-call behaviour, refusal patterns and edit granularity in Codex. Treat replacements as new models, not drop-ins.
Re-baseline limits and cost. Usage limits differ by plan and model; Astra consumes more credits per message than Sol in ChatGPT.
API users: plan anyway. Move gpt-5.5 calls to gpt-5.6-sol or gpt-6-astra in a canary route now; you will have months, not weeks, when the API notice comes, but you will have to do it. Guide: How to run an AI model upgrade safely.
Watch for the Astra long-context premium. Prompts above 272,000 tokens reprice; trim context you were passing to GPT-5.5 rather than filling Astra’s window.

What happens on October 14 if you do nothing

In ChatGPT, GPT-5.5 vanishes from the model picker and existing chats continue on your plan’s default model (Luna on Free, Sol on paid) — expect subtle style changes. In Codex, sessions pinned to GPT-5.5 will fail to start or fall back, depending on client version; update to a current Codex build and set the model explicitly. API calls keep working.

Precedents

GPT-4.5 retirement, June 27, 2026 — API and ChatGPT together, ~3 months’ notice.
o3 retired August 26, 2026 — replaced by GPT-5.6 tiers.

The pattern: product surfaces first, API later, with a named replacement each time. GPT-5.5’s API date will come; the October 14 notice is your early warning.