So the Claude Code Opus 5.5 default switch has landed: as of version 2.1.280, released 22 September 2026 per the official changelog, Claude Code now runs Opus 5.5 as its default Opus model — and Pro plans got moved from Sonnet to Opus at the same time. I run Claude Code daily for SEO automation, so here is what actually changed, what it costs, and the settings worth checking today.
Short answer
- Claude Code 2.1.280 (22 September 2026) makes Claude Opus 5.5 (
claude-opus-5-5) the default Opus model. - It ships with a 1M token context window.
- API pricing: $4 / $20 per million tokens, with cache reads at $0.20/Mtok.
- Pro and Team Standard plan defaults changed from Sonnet to Opus in the same release.
- Saved effort levels do not carry over — Opus 5.5 starts at default effort, so re-check /effort.
Claude Code Opus 5.5 default: what the 2.1.280 changelog actually says
Per the official Claude Code changelog entry for version 2.1.280 (22 September 2026), Claude Opus 5.5 — model ID claude-opus-5-5 — is now the default Opus model, with a 1M token context window and API pricing of $4 per million input tokens and $20 per million output tokens, plus $0.20 per million tokens for cache reads.
Just as important for most users: the same release changed the default model on Pro and Team Standard plans from Sonnet to Opus, bringing them in line with Max, Team Premium and Enterprise. If you are on Pro and Claude Code suddenly feels different this week, this is why — you were moved onto the bigger model by default.
| What changed in 2.1.280 | Detail (from the official changelog) |
|---|---|
| Default Opus model | Claude Opus 5.5 (claude-opus-5-5) |
| Context window | 1M tokens |
| Pricing | $4 / $20 per Mtok, $0.20/Mtok cache reads |
| Plan defaults | Pro and Team Standard moved from Sonnet to Opus |
| Effort levels | Old saved effort settings do not carry to new models; Opus 5.5 starts at default |
| Extras | Expanded mouse support in fullscreen mode; new MCP description-length variable |
What the 1M context window changes in practice
A million tokens of context in the default model means whole-repo work — long refactors, multi-file audits, big content batches — without the constant compaction dance. For SEO work specifically, it is the difference between feeding a model one page at a time and handing it your entire content cluster plus crawl data in a single session. Combine it with the recent AGENTS.md support added in 2.1.277 and you can point Claude Code at a project it has never seen and have it pick up your standards immediately.
🔥 Want this set up without the guesswork? If you want Claude Code running your SEO content production on the new Opus 5.5 default — prompts, agents, publishing pipelines, the lot — you do not have to figure it out alone. That is exactly what we do inside the AI Profit Boardroom — 3,700+ members, four live calls per week, daily tutorials, done-for-you templates and a 30-day roadmap.
Prefer to talk it through one-on-one first? Book a free SEO strategy session and we will map out your next steps together.
Pricing: what the new default costs to run
At $4 in / $20 out per million tokens, Opus 5.5 sits well below what flagship-tier models cost a year ago, and the $0.20/Mtok cache reads are the number to watch if you run agents: well-structured, cache-friendly prompts get dramatically cheaper on repeat calls. For terminal users on Pro or Max plans, usage is covered by the plan — the per-token numbers matter when you hit the API or the Agent SDK.
Note the changelog also flags that effort levels saved before per-model support existed no longer apply to new models — Opus 5.5 starts at the default effort. If you had tuned effort down to stretch usage, re-check it: my guide to the /effort command covers the settings, and if you are weighing this model against Anthropic’s other tier, see my Claude Opus 5 vs Fable 5 comparison.
How to change the Claude Code Opus 5.5 default if you do not want it
Nothing locks you in. Run /model inside Claude Code to pick a different model for the session, and /effort to tune how hard the model thinks. Teams that standardise on a specific model for cost reasons can keep doing exactly that — the 2.1.280 change only moves the default, not your options. And because the same week’s releases also made auto mode’s safety classifier run server-side for API and Enterprise users (2.1.278, per the changelog), the out-of-the-box experience is both bigger-brained and less overhead-billed than before.
The workflow layer is where the real wins live though — the model default is just the engine. Inside the AI Profit Boardroom we keep a live, updated playbook of Claude Code SEO workflows, and you can always book a free SEO strategy session to see which of them fit your site.
The bottom line on the Claude Code Opus 5.5 default
This is the biggest default-model shift Claude Code has had in months: a 1M-context Opus at $4/$20 per Mtok, on by default even for Pro users. Check your /model and /effort settings once, then take advantage — the larger context plus cheap cache reads reward bigger, better-structured workflows rather than lots of small ones. Everything here is sourced from the official Claude Code changelog dated 22 September 2026, and I will update this page as the rollout evolves.
FAQ: claude code opus 5.5 default
When did Opus 5.5 become the default in Claude Code?
In Claude Code version 2.1.280, dated 22 September 2026 in the official changelog. Claude Opus 5.5 (model ID claude-opus-5-5) is now the default Opus model.
How big is the Opus 5.5 context window?
The changelog lists a 1M (one million) token context window for Opus 5.5 in Claude Code.
What does Opus 5.5 cost?
Per the changelog, pricing is $4 per million input tokens and $20 per million output tokens, with cache reads at $0.20 per million tokens.
Which plans got the new default?
The same release changed the default model for Pro and Team Standard plans from Sonnet to Opus, matching what Max, Team Premium and Enterprise already had.
Do my saved effort settings carry over to Opus 5.5?
No. Effort levels saved before per-model support no longer apply to new models, so Opus 5.5 starts at the default effort level. You can re-set it with /effort.
Can I switch away from the Claude Code Opus 5.5 default?
Yes. The /model command lets you pick a different model for the session, and effort can be tuned per model. Nothing forces you to stay on the default.
Related reading
- Claude Code AGENTS.md support: what changed
- Claude Code effort level: full guide to /effort
- Claude Opus 5 vs Fable 5: which wins?
Next steps: The Opus 5.5 default gives every Claude Code user a bigger engine — the leverage is in the workflows you run on it. Join 3,700+ members inside the AI Profit Boardroom for the live calls, daily tutorials and done-for-you templates, or book a free SEO strategy session and get a personal plan for your site.
About the author
Julian Goldie is an SEO agency owner with 10+ years in SEO, 394K+ subscribers on YouTube, a 100% job-success score on Upwork, 75K+ community members across his groups, and the author of a best-selling SEO book. He runs the AI Profit Boardroom community, and you can book a free SEO strategy session with his team any time.
Last updated September 2026. This is the living guide to claude code opus 5.5 default — it gets updated as the tools change.
