GPT-5.5 Deprecated: Retirement Date, Replacements (2026)

As of today, October 8, 2026, GPT-5.5 still works everywhere it did last month — but it is now a deprecated model with two published removal dates. OpenAI's model documentation is unambiguous: "On October 14, 2026, GPT-5.5 will retire from ChatGPT, ChatGPT Work, and Codex on all plans, including consumer, Business, Enterprise, and Edu plans." Six days after that, on October 19, 2026, GitHub removes GPT-5.5 from every Copilot experience — chat, inline edits, ask and agent modes, and code completions. So if you searched whether gpt-5.5 is deprecated: yes, on both product platforms, with different replacement models on each side — and neither date touches the OpenAI API.

The two replacement answers are where it gets confusing, because the platforms disagree. OpenAI's own docs point GPT-5.5 users at GPT-6 Sol (paid plans) and GPT-6 Luna (Free and Go), with GPT-6.1 Sol as the current Codex default. GitHub's Copilot changelog maps GPT-5.5 to GPT-5.6 Sol — a previous-generation model from an older family. Both are "Sol." Neither is the same model. Below: both timelines in one table, every official replacement mapped, why the two platforms point in different directions, what Copilot admins need to do before October 19, and a clear line between what we verified and what we couldn't.

Quick answer

• Is GPT-5.5 deprecated? Yes, on the product side. OpenAI's model docs announce the retirement from ChatGPT, ChatGPT Work, and Codex on October 14, 2026; GitHub removes it from all Copilot experiences on October 19, 2026.
• Does it still work today? Yes. As of October 8, 2026, GPT-5.5 is listed as a "previous-generation flagship model" and remains usable — the removal dates are in the future.
• What about the API? Not affected. The same documentation states: "This retirement does not apply to the OpenAI API," and notes GPT-5.5 "remains available on the OpenAI API."
• What replaces it? It depends where you use it. ChatGPT paid plans get GPT-6 Sol (gpt-6-sol); ChatGPT Free and Go get GPT-6 Luna (gpt-6-luna); Codex defaults to GPT-6.1 Sol; GitHub Copilot maps GPT-5.5 to GPT-5.6 Sol.
• gpt-5.6-sol is not gpt-6.1-sol. The GPT-5.6 family is the previous generation, which OpenAI says remains available only "during the rollout"; GPT-6.1 Sol is the current flagship and the bundled default in Codex since CLI 0.159.1 (September 29), reaffirmed in 0.161.0 (October 7).
• What should you do? ChatGPT/Codex users: the switch is platform-side, but scrub gpt-5.5 from workspace defaults, saved settings, custom agents, scheduled tasks, and scripts — OpenAI's own migration advice. Copilot admins: confirm the replacement models are enabled through model policies before October 19. Details below.

What's retiring, and when

Two schedules, two owners. OpenAI retires GPT-5.5 from its consumer and work surfaces on October 14; GitHub pulls it — alongside five other models — from Copilot on October 19. Both dates land within eleven days of this post.

Two reading notes on that table. First, the Copilot removal is a six-model sweep, not a GPT-5.5-specific event — GitHub's September 18 changelog entry is addressed to Copilot Enterprise and Copilot Business customers and covers all of the rows below the first one at the same moment. Second, the scopes differ: OpenAI's retirement covers the ChatGPT apps, ChatGPT Work, and Codex sign-in flows on every plan tier, while GitHub's removal applies across all Copilot experiences on the IDE, CLI, and coding-agent side. The OpenAI API sits outside both lists entirely.

What replaces GPT-5.5?

Here is the full mapping, including the surface most people actually mean when they ask the question:

On the OpenAI side, the destination is clearly the GPT-6 family. The models page keeps the GPT-5.6 Sol, Terra, and Luna trio around only as transitional options — its exact wording is that they "remain available during the rollout" — while the per-plan replacement guidance points straight at gpt-6-sol and gpt-6-luna. The changelog fills in the default-model story: Codex CLI 0.159.1 added GPT-6.1 Sol as the default in the bundled catalog (and Amazon Bedrock catalogs) on September 29, and 0.161.0 extended that to the bundled and Bedrock catalogs on October 7. OpenAI's September 29 release notes describe GPT-6.1 Sol as offering "near-Astra performance for complex work at a lower cost than Astra" — for what that costs and how it stacks up, see our GPT-6.1 Sol pricing and context window breakdown.

The confusion to defuse is the name collision. Search trends and community threads show people conflating gpt-5.6-sol with gpt-6.1-sol; they are two generations apart despite the shared "Sol" branding. GPT-6 Sol shipped September 22, and GPT-6.1 Sol is its DevDay upgrade from September 29 — same headline price of $2 and $10 per million tokens, with cheaper cache reads on the newer version. GPT-5.6 Sol belongs to the older 5.6 family and, on OpenAI's own docs, exists only as a rollout-period holdover. Neither is GPT-5.5's successor everywhere — which brings us to the disagreement.

Why OpenAI and GitHub point to different replacements

This is the part nobody else seems to say plainly, so let's lay it out:

• OpenAI's guidance sends GPT-5.5 users to the GPT-6 family. The models page names gpt-6-sol for paid plans and gpt-6-luna for Free and Go, and treats the 5.6 family as a temporary bridge.
• GitHub's changelog maps GPT-5.5 to GPT-5.6 Sol — and, notably, maps GPT-5.4 to GPT-5.6 Sol and GPT-5.4 mini to GPT-5.6 Luna too. The pattern is "the next model within the family Copilot already carries," not "OpenAI's current flagship."
• GitHub doesn't explain the choice. The entry calls the mappings "suggested alternatives" and stops there. We can observe that GPT-6.1 Sol became available in Copilot on September 29, so a GPT-6-class mapping was possible — GitHub chose 5.6 anyway. Why is not documented, and we won't invent a reason.
• The practical consequence: "the GPT-5.5 replacement" is not one model. Follow OpenAI's docs and you land on GPT-6 or GPT-6.1 Sol; stay inside Copilot and you land on GPT-5.6 Sol; use the API and nothing changes at all.

If you split your week between Copilot and Codex, expect the two tools to feel different after mid-October even though "the same model" retired from both. That is not your configuration breaking — it's the two platforms resolving the same retirement differently.

The earlier 2026 retirements, for context

GPT-5.5's removal is the last step of a wave, not a surprise announcement. Everything below is from the same two official sources:

The docs also list GPT-5.2 and GPT-5.3-Codex as already deprecated in Codex with ChatGPT sign-in — older history, but worth knowing if you're maintaining long-lived scripts. When Codex Spark retired on September 14, we published a guide to Codex Spark alternatives; the same selection logic applies to GPT-5.5 now, just with the GPT-6 family as the destination.

What Copilot admins need to do before October 19

GitHub's entry is written for Copilot Enterprise and Copilot Business administrators, and the mechanics matter more than usual because of how default models work in Copilot:

1. Check your default-model stance first. Under Copilot's default model enablement, GitHub states that "the suggested alternatives are automatically enabled" for these plans — unless an administrator has turned off the global default or explicitly disabled the specific model. If you never touched either setting, the replacements will simply appear in the Copilot Chat model picker on their own.
2. If you did lock things down, re-open them via model policies. Admins who disabled the global default (or a specific model) grant access to the replacements through model policies in Copilot settings — that's the control surface GitHub names for Enterprise. Enable GPT-5.6 Sol (or the relevant substitute for each retired model) explicitly.
3. Update workflows and integrations that reference GPT-5.5. Saved prompts, agent configurations, internal documentation, and CI scripts that pin a model by name all break silently on October 19 — the changelog's own advice is to update workflows and integrations to supported models before the date.
4. Don't look for a removal step. GitHub explicitly notes that no action is needed to remove the deprecated models — they disappear from the picker automatically. The only preparation is on the replacement side.
5. Enterprise customers with questions can contact their GitHub account team, per the same entry.

One planning note: because the October 19 sweep also removes Gemini 3.7 Flash, GPT-5.4, GPT-5.4 mini, GPT-5 mini, and Grok 4.5, a policy check done only for GPT-5.5 can still leave a team stranded on another retired model. Inventory all six before you close the ticket.

What happens to API users

Nothing, on these dates. OpenAI draws the line explicitly: "This retirement does not apply to the OpenAI API." The same page lists GPT-5.5 under its previous-generation models with the note that it "remains available on the OpenAI API" — as of October 8, 2026, that is still the live state.

API model sunsets are handled on OpenAI's separate deprecations page, with their own timeline and notice periods. We could not find — and therefore cannot cite — a published API deprecation date for gpt-5.5 as of this writing. The honest position: the October 14 ChatGPT retirement is not an API signal, and anyone extrapolating it to their API bill is guessing. Watch the deprecations page, not the consumer announcement.

If this whole exercise has you re-costing your stack anyway, the numbers worth seeing are the ones outside the GPT family: GPT-6.1 Sol runs $2/$10 per million tokens, which is roughly an order of magnitude above DeepSeek's rates — our DeepSeek V4 Flash guide covers the budget end, and our Claude Code pricing analysis does the subscription-side math if you're weighing an ecosystem move rather than a model swap.

What we couldn't verify

Keeping with house style, the gaps:

• No API deprecation date for GPT-5.5. The API is excluded from this retirement; no future API sunset is published anywhere we could verify.
• GitHub's reasoning for GPT-5.6 Sol. The changelog documents the mapping but not the rationale. Any explanation you read elsewhere is inference.
• How long the GPT-5.6 family stays available in ChatGPT and Codex. The docs only say the models "remain available during the rollout" — no end date is given.
• The current default model inside ChatGPT Work. OpenAI's September 29 announcement covered GPT-6.1 Sol in Codex and ChatGPT Work, and the Codex CLI default is confirmed by the changelog — but we couldn't independently inspect ChatGPT Work's picker, and the models page names gpt-6-sol as the per-plan replacement. Treat Work's default as unconfirmed.

FAQ

Is GPT-5.5 deprecated?

Yes — on the product side. It retires from ChatGPT, ChatGPT Work, and Codex on all plans on October 14, 2026, and GitHub removes it from all Copilot experiences on October 19, 2026. It is not deprecated on the OpenAI API. As of October 8, 2026, it still runs everywhere and is listed as a previous-generation flagship model.

When does GPT-5.5 retire?

Two dates, two platforms. October 14, 2026 for ChatGPT, ChatGPT Work, and Codex — all plans, including consumer, Business, Enterprise, and Edu. October 19, 2026 for GitHub Copilot, where the removal spans chat, inline edits, ask and agent modes, and code completions on Enterprise and Business.

What replaced GPT-5.5?

It depends on the surface: ChatGPT paid plans move to GPT-6 Sol, Free and Go move to GPT-6 Luna, Codex defaults to GPT-6.1 Sol, and GitHub Copilot maps GPT-5.5 to GPT-5.6 Sol. The full mapping table is above — the Copilot answer is a different generation than the OpenAI answer.

Is GPT-6.1 Sol the same as GPT-5.6 Sol?

No. They are two generations apart despite the shared "Sol" name. GPT-5.6 Sol is a previous-generation 5.6 family model — the one GitHub picked as Copilot's GPT-5.5 replacement. GPT-6.1 Sol is OpenAI's current flagship, the bundled default in Codex since September 29 (reaffirmed October 7), priced at $2/$10 per million tokens with a 1.05M-token context window.

Do I need to do anything in Codex before October 14?

The model transition itself is handled by the platform — GPT-5.5 disappears from the picker and sessions move to available models. What OpenAI asks you to do is migrate gpt-5.5 references out of workspace defaults, saved settings, managed configurations, custom agents, scheduled tasks, and scripts, including codex exec --model gpt-5.5 invocations. Our Codex model picker guide shows how to pin the new default, and the Codex CLI tutorial covers the /model flow end to end.

What about GPT-5.4 and GPT-5.4-mini?

Already gone from Codex with ChatGPT sign-in — they retired August 31, 2026, replaced by GPT-6 Sol and GPT-6 Luna. On GitHub Copilot they survive until October 19, 2026, when GPT-5.4 maps to GPT-5.6 Sol and GPT-5.4 mini maps to GPT-5.6 Luna.

Does the GPT-5.5 retirement affect the OpenAI API?

No. The official wording is that the retirement "does not apply to the OpenAI API," and GPT-5.5 "remains available on the OpenAI API." API deprecations are announced on a separate page with their own timeline; no API sunset date for GPT-5.5 was verifiable as of October 8, 2026.

Related reading

• GPT-6.1 Sol pricing and context window — the model most GPT-5.5 users will land on in Codex, costed in full
• Codex model picker tutorial — pin a new default before October 14
• Codex Spark alternatives — the September retirement, and how to choose a successor
• Claude Code pricing, examined — the cross-ecosystem math if you're switching tools, not just models
• DeepSeek V4 Flash guide — the budget route this site runs on