GPT-5.5 Leaves ChatGPT and Codex on October 14: What to Switch To, and What It Does to Your Limits (2026)

Five days. That’s how long a lot of Codex setups have left before a model name they typed once and forgot about stops pointing anywhere.

GPT-5.5 launched on April 23, 2026 and was OpenAI’s headline model for most of the year. On October 14 it leaves every ChatGPT surface. The confusing part isn’t the date. It’s that the replacement advice changed in the middle, and a lot of guides still repeat the September version.

This page is laid out as plain questions and straight answers, the ones people are actually asking in forums and support threads this week.

Questions Answered Here

• When exactly does GPT-5.5 stop working, and where?
• Does the GPT-5.5 retirement affect the OpenAI API?
• Which model should replace GPT-5.5 now?
• Will the replacement eat my Codex limits faster?
• How do I switch Codex off GPT-5.5 before October 14?
• What happens to my regular ChatGPT chats?
• Where else could “gpt-5.5” still be hiding?
• Tips
• Warnings
• FAQ
• Sources

When exactly does GPT-5.5 stop working, and where?

GPT-5.5 is retired from ChatGPT, ChatGPT Work, and Codex on October 14, 2026, across consumer, Business, Enterprise, and Edu plans, according to OpenAI’s ChatGPT Learn models page.

That covers three places people use it. The chat window. The newer Work mode on web and desktop. And Codex, whether you run the desktop app, the IDE extension, or the CLI while signed in with a ChatGPT account.

OpenAI announced the date in mid-September, in the same batch of changes that stopped ChatGPT Plus and Pro from switching to Thinking on its own. Mixed News covered both changes on September 14.

So the clock started almost a month ago. Most people just didn’t notice.

Does the GPT-5.5 retirement affect the OpenAI API?

No. The October 14, 2026 retirement of GPT-5.5 applies only to ChatGPT, ChatGPT Work, and Codex sessions signed in with a ChatGPT account. The model stays on the OpenAI API, and Codex sessions that authenticate with an API key keep it too.

That distinction matters if you build things. An app calling gpt-5.5 through the API keeps working on the 15th. A teammate running the Codex CLI on their Plus login, with gpt-5.5 pinned in a config file, is the one who gets surprised.

Check which login your scripts use. Same tool, two very different outcomes.

Which model should replace GPT-5.5 now?

OpenAI’s models page, as of October 2026, tells Plus, Pro, Business, Enterprise, and Edu users to switch from GPT-5.5 to GPT-6 Sol, and tells Free and Go users to use GPT-6 Luna in the desktop app.

Here’s where people get tripped up. The September coverage named a different replacement: GPT-5.6 Sol. Then OpenAI shipped GPT-6 Sol and GPT-6 Luna on September 22, and GPT-6.1 Sol at DevDay on September 29. When I checked OpenAI’s current models page against the September articles, I found that the recommended name had moved on twice. Nobody went back and updated the old guides.

So if a blog post or a coworker says “just switch to 5.6 Sol,” that advice is about three weeks stale.

GPT-6.1 Sol is the newer Sol version, and it became the default model in the Codex CLI with release 0.161.0 on October 7, per the ChatGPT and Codex changelog. If you’re on a recent CLI and never pinned a model, you’re probably already on it. We covered why it doesn’t appear in regular chat in GPT-6.1 Sol Not Showing in ChatGPT or Codex?

Will the replacement eat my Codex limits faster?

Probably not, unless you jump to Astra. On a ChatGPT Plus plan, OpenAI estimates about 15 to 150 local Codex messages per five hours on GPT-6 Sol, 15 to 160 on GPT-6.1 Sol, and only 5 to 45 on GPT-6 Astra, according to OpenAI’s Codex pricing page.

Those ranges are wide because a one-line fix and an hour-long refactor both count as “a message.” Still, the ratios tell you something. When I compared the credit rates on the same page, Astra costs exactly five times what GPT-6.1 Sol does per million tokens, for input and output alike.

Source: OpenAI Codex pricing page, standard speed, checked October 9, 2026. Credit rates apply to purchased credits and pay-as-you-go; included subscription usage uses its own multipliers.

One more thing to watch. Fast mode bills purchased credits at 2x the standard rate and Ultrafast at 6x, per the same pricing page. If you buy extra credits, check that speed setting before you blame the new model.

Honestly, for most Plus users the switch is close to neutral.

How do I switch Codex off GPT-5.5 before October 14?

To move the Codex CLI off GPT-5.5, set model = "gpt-6.1-sol" (or another current model) in your config.toml, or pass codex -m gpt-6.1-sol, as shown on OpenAI’s Codex models page.

1. Update the CLI first. Release 0.161.0 (October 7, 2026) is the one that made GPT-6.1 Sol the default.
2. Open your config file. Search it for gpt-5.5. Replace the model line.
3. Check the session picker. Type /model inside a session to confirm what’s actually running and adjust reasoning effort.
4. Re-run one real task. Pick something you ran last week and compare. Not a toy prompt.
5. Write down the old setting. If something regresses, you’ll want to know what changed.

If you prefer the GPT-6 Sol name OpenAI lists as the official replacement, use whichever Sol entry your /model list actually shows. Model names in a config must match what your account offers.

What happens to my regular ChatGPT chats?

Regular ChatGPT Chat will simply stop offering GPT-5.5 after October 14, 2026; OpenAI’s models page says Astra, Sol, and Luna are Work and Codex models and don’t appear in Chat, and it doesn’t spell out how old conversations are handled.

OpenAI hasn’t written down whether old GPT-5.5 threads keep working as-is or continue on a different model. So don’t count on any particular behavior for a conversation you depend on.

Two practical moves. Export or copy any long thread you still lean on. And pick your model and thinking level by hand from now on, because Plus and Pro no longer auto-switch to Thinking since the September 14 change.

Where else could “gpt-5.5” still be hiding?

A pinned GPT-5.5 reference can sit in five places that OpenAI’s models page tells users to update: workspace defaults, saved configurations, custom agents, scheduled tasks, and scripts.

Most people skip the last two and regret it. A scheduled task that ran fine every morning for months is exactly the thing nobody opens again.

• Codex config.toml and any per-project overrides
• Shell aliases like alias cx="codex -m gpt-5.5"
• CI jobs that call Codex with a ChatGPT login
• Scheduled tasks in ChatGPT or Codex
• Workspace defaults set by a Business or Enterprise admin
• Team docs and onboarding notes telling new hires which model to pick

Copilot users have a separate deadline, by the way. GitHub drops its own GPT-5.5 option on October 19, which we broke down in the Copilot guide linked below.

Tips

• Search your whole home folder and repos for the string gpt-5.5. It takes ten seconds.
• Start with GPT-6.1 Sol in Codex. Only move up to Astra for jobs where Sol clearly fails.
• Use Luna for bulk, repetitive edits. Its output rate is one-twentieth of 6.1 Sol’s.
• Enterprise and Edu admins: enable GPT-6.1 Sol before the 14th, or your users will see only GPT-6 Sol.

Warnings

• Don’t copy “GPT-5.6 Sol” from September guides into a config. Use a name your /model list shows today.
• Switching your Codex login to an API key keeps GPT-5.5 alive, but you pay per token instead of using plan limits.
• OpenAI’s message estimates are ranges, not guarantees. Long agent runs burn through them faster.
• Retirement dates can shift. Re-check OpenAI’s models page if you’re reading this after October 14.

FAQ

Can I keep using GPT-5.5 after October 14, 2026?

Only through the OpenAI API or Codex signed in with an API key. ChatGPT, ChatGPT Work, and Codex on a ChatGPT login lose it on October 14 on every plan.

Is GPT-6 Sol the same as GPT-6.1 Sol?

No. GPT-6.1 Sol is a newer Sol version launched on September 29, 2026 and is the Codex CLI default since October 7. OpenAI names GPT-6 Sol as the official GPT-5.5 replacement for paid plans.

What should Free and Go users switch to?

OpenAI recommends GPT-6 Luna in the ChatGPT desktop app for Free and Go plans. It is the lowest-cost model in the lineup, so expect shorter, simpler answers on hard tasks.

Sources

• OpenAI ChatGPT Learn — Models (availability and GPT-5.5 retirement)
• OpenAI — Codex pricing and usage limits
• OpenAI — Codex models and how to change them
• OpenAI — ChatGPT and Codex changelog (Codex CLI 0.161.0, October 7, 2026)
• Mixed News — ChatGPT Plus and Pro stop switching to Thinking, GPT-5.5 retires October 14

Fact-checked against OpenAI’s ChatGPT Learn models page, Codex pricing and models pages, and the ChatGPT and Codex changelog as of October 9, 2026. Model names, limits, and dates may change after publication.