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September 16, 2026 · By JayyRedd

GPT-5.5 Retirement: Leaves ChatGPT Oct 14, the API Keeps It

Quick answer: OpenAI is removing GPT-5.5 from ChatGPT, ChatGPT Work and Codex on October 14, 2026, on every plan. It is not being shut off in the API. OpenAI Developers confirmed that GPT-5.5 stays available on the OpenAI API Platform and in Codex sessions authenticated with an API key, and as of September 16, 2026 there is no API shutdown date for it. If you use Codex signed in with your ChatGPT account, switch to GPT-5.6 Sol or GPT-6 Astra before October 14.

Last verified September 16, 2026. Every date and quote below links to its source at the bottom of the page.

What OpenAI announced

On September 15, 2026, the ChatGPT account posted:

On October 14, it's time to say farewell to GPT-5.5 in ChatGPT, ChatGPT Work, and Codex across all plans.

If you use GPT-5.5 in Codex, switch to GPT-5.6 Sol or GPT-6 Astra.

Thanks for everything, 5.5 🫡

Thirty-seven seconds later, the OpenAI Developers account quote-posted it with the part most people missed:

GPT-5.5 will remain available via the OpenAI API Platform and in Codex sessions authenticated with an API key.

So this is a product retirement, not an API shutdown. Those are two different events, and mixing them up is how people panic for no reason.

Who loses GPT-5.5 on October 14, and who keeps it

Where you use GPT-5.5 After October 14, 2026
ChatGPT (every consumer plan) Removed from the model picker
ChatGPT Work Removed
Codex, signed in with your ChatGPT account Removed. Switch to GPT-5.6 Sol or GPT-6 Astra
Codex, authenticated with an API key Still available
The OpenAI API Platform Still available, with no shutdown date announced

Does this affect me?

If you just use ChatGPT and take whatever model it gives you: no. Your new chats land on the current default. We've seen this exact move already this year. When GPT-5.2 left ChatGPT on June 12, 2026, existing conversations simply continued on the matching GPT-5.5 model. Nobody lost a thread.

You have work to do if you:

  • Pinned GPT-5.5 in the ChatGPT model picker and chose it on purpose every time
  • Built a workflow in Codex while signed in with your ChatGPT account
  • Have scripts or agent setups that run through ChatGPT-signed Codex with gpt-5.5 typed into them

You're fine if you: call GPT-5.5 through the OpenAI API, or use Codex with an API key. Nothing breaks for you on October 14.

What replaces GPT-5.5?

OpenAI's own guidance names two replacements for Codex users:

  • GPT-5.6 Sol, the top model in the GPT-5.6 family, which shipped July 9, 2026 in three variants: Luna (fastest and cheapest), Terra (balanced) and Sol. It's the one to reach for on frontier coding work.
  • GPT-6 Astra, OpenAI's current flagship. It opened to approved users on September 3, 2026 and became generally available the next day.

The timeline: five months in the product

Date What happened
April 23, 2026 GPT-5.5 launches (Thinking and Pro, paid tiers first), about six weeks after GPT-5.4
July 9, 2026 GPT-5.6 ships, and 5.5 becomes the previous generation
September 15, 2026 Retirement from ChatGPT, ChatGPT Work and Codex announced; OpenAI Developers confirms the API keeps it
October 14, 2026 GPT-5.5 leaves the apps

That's about five months in the product and 29 days of notice.

Why 29 days of notice doesn't break OpenAI's own policy

OpenAI publishes minimum notice periods on its deprecations page:

  • Generally available models: at least 6 months
  • Specialized variants (chat, Codex and deep research variants): at least 3 months
  • Preview models: much shorter, such as 2 weeks

Twenty-nine days matches none of those, and that isn't a contradiction. That policy covers the API. It doesn't cover the ChatGPT app. The consumer products run on a much faster clock:

  • June 2026: GPT-5.2 left ChatGPT
  • August 31, 2026: GPT-5.4 and GPT-5.4 mini left ChatGPT-signed Codex. API-key Codex and the API kept them.
  • October 14, 2026: GPT-5.5 leaves ChatGPT, ChatGPT Work and ChatGPT-signed Codex, and again the API keeps it.

The GPT-5.4 retirement in August was the same split we're seeing now: same model, same tool, two different answers depending on how you logged in.

What to do before October 14

  1. Normal ChatGPT user: nothing. Close the tab.
  2. Codex signed in with your ChatGPT account, or scripts running through it: find every gpt-5.5 reference and switch to gpt-5.6-sol or gpt-6-astra before October 14.
  3. On the API, or Codex with an API key: you keep GPT-5.5. Keep an eye on the deprecations page. When OpenAI does set an API shutdown date, it will be listed there, under the notice periods above.

Why OpenAI is doing this

OpenAI didn't give a reason in either post. The likely one is the same as every other product sunset this year: serving capacity and the model picker both get simpler when the apps run only the current stack, the GPT-5.6 family and GPT-6 Astra. Once 5.6 shipped in July, 5.5 was already last generation.

Not everyone is happy about it

A thread in OpenAI's own developer forum asks OpenAI to keep GPT-5.5 as a legacy option in Codex and to give 90 days' notice instead of 29. Developers there report that the GPT-5.6 models over-reason, widen the scope of what they were asked to do, and use more time and quota for output that isn't proportionally better.

That's their experience, not a benchmark, and I'm not going to tell you 5.6 is worse. But for anyone who built a ChatGPT-signed Codex workflow around 5.5's behavior, 29 days isn't much room.

Frequently asked questions

When is GPT-5.5 being retired?

GPT-5.5 leaves ChatGPT, ChatGPT Work and Codex on October 14, 2026, across all plans. OpenAI announced it on September 15, 2026.

Is GPT-5.5 still available in the API?

Yes. OpenAI Developers confirmed that GPT-5.5 will remain available via the OpenAI API Platform and in Codex sessions authenticated with an API key. As of September 16, 2026, OpenAI's deprecations page lists no API shutdown date for GPT-5.5.

Will my API calls to gpt-5.5 stop working on October 14?

No. October 14 is the date GPT-5.5 leaves the ChatGPT and Codex apps, not the API. Some coverage has claimed API calls will return errors, but that contradicts OpenAI's own statement and cites no OpenAI source.

What should I use instead of GPT-5.5 in Codex?

OpenAI recommends switching to GPT-5.6 Sol or GPT-6 Astra. If you run Codex with an API key instead of your ChatGPT account, you can keep using GPT-5.5.

Will I lose my old ChatGPT conversations that used GPT-5.5?

OpenAI hasn't detailed this for GPT-5.5 specifically. When GPT-5.2 was removed from ChatGPT on June 12, 2026, existing conversations continued on the matching newer model, and that's the likely pattern here.

Why is OpenAI only giving 29 days of notice?

OpenAI's 3-month and 6-month minimum notice periods apply to API model deprecations. ChatGPT and ChatGPT-signed Codex aren't covered by that policy, and product surfaces have retired models much faster throughout 2026.

Is GPT-5.5 available on the ChatGPT free plan after October 14?

No. The retirement applies to ChatGPT across all plans, so GPT-5.5 won't be in the model picker on any plan after October 14, 2026.

Sources

If you're adapting your own setup to GPT-6 Astra, the AGENTS.md and skills rethink for GPT-6 Astra is the next read. And if you want help building workflows that survive the next model swap, that's what we do inside the AI Creators Roundtable.