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Claude models Sonnet 4.5 Sonnet 5.5 Accuracy

Claude Sonnet 4.5 Retires November 30, 2026: Deprecated September 30, Replacement Sonnet 5.5

By Scott Bissett  ·  Published: September 24, 2026  ·  Updated: September 30, 2026  ·  Dates on this page are served from data and checked against Anthropic's model deprecations page daily

Claude Sonnet 4.5 now has a retirement date. On September 30, 2026 Anthropic moved claude-sonnet-4-5-20250929 to Deprecated on its model deprecations page, set the retirement date to November 30, 2026, and named claude-sonnet-5-5 as the recommended replacement. The model keeps working until the retirement date; after it, requests fail. That is 61 days of notice, one more than the 60 Anthropic commits to for publicly released models.

What changed since this guide was first published. On September 24 the page listed Sonnet 4.5 as Active with a tentative retirement date of not sooner than September 29, 2026, and this guide explained why that was a floor and not a retirement. The floor passed on the 29th with nothing announced. The deprecation notice came the next day, with a real date two months out, which is exactly the shape every earlier Claude retirement took. Our data served the model as supported with no end date until today; as of this build it serves the deprecation and retirement dates from Anthropic's page.
Quick answer: The Claude (Anthropic) Claude Sonnet 4.5 end-of-life (EOL) date is November 30, 2026. Active support ended on September 30, 2026; security fixes continue until the end-of-life date. Every Claude (Anthropic) version's release and end-of-support date is on the Claude (Anthropic) lifecycle page.

Anthropic's four lifecycle states

Anthropic defines the terms on the page itself. Active: fully supported and recommended. Legacy: no longer receiving updates and may be deprecated in the future. Deprecated: still functional but no longer recommended; Anthropic provides a recommended replacement and assigns a retirement date. Retired: the model is no longer available for use, and requests to retired models fail.

Two rules sit around those states. Anthropic notifies customers with active deployments of upcoming retirements, providing at least 60 days' notice before model retirement for publicly released models. And the dates on the page apply to Anthropic-operated platforms (the Claude API, Claude Platform on AWS and Microsoft Foundry); Amazon Bedrock and Google Cloud set their own retirement schedules, so a model's status and dates can differ there.

Sonnet 4.5 is now in the Deprecated state: functional, not recommended, replacement named, retirement day fixed. Haiku 4.5 and Opus 4.5 are still Active, and their 2026 dates are still floors.

Running Claude past end of life?
Extended support past the official EOL date exists for many products in this position — whether it covers Claude is exactly what we check. Tell us where to reach you and we’ll reply with matched options and pricing guidance — or an honest “no vendor covers this.” Free, no obligation.

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What the table says, model by model

API model nameReleasedStateDeprecatedRetirement
claude-sonnet-4-5-202509292025-09-29Deprecated2026-09-302026-11-30 (replacement: claude-sonnet-5-5)
claude-haiku-4-5-202510012025-10-15ActiveNoneNot sooner than October 15, 2026 (floor)
claude-opus-4-5-202511012025-11-24ActiveNoneNot sooner than November 24, 2026 (floor)
claude-opus-4-1-202508052025-08-05Retired2026-06-052026-08-05
claude-sonnet-4-202505142025-05-22Retired2026-04-142026-06-15
claude-opus-4-202505142025-05-22Retired2026-04-142026-06-15
claude-3-7-sonnet-202502192025-02-24Retired2025-10-282026-02-19
claude-3-5-haiku-202410222024-10-22Retired2025-12-192026-02-19
claude-3-haiku-202403072024-03-13Retired2026-02-192026-04-20

The Deprecated column is the day Anthropic notified developers; the Retirement column is the day requests start failing. For the two Active models the last column is Anthropic's floor, printed as text because it is not a date in our data. The Sonnet 4.5 and retired rows are served from data and re-read from Anthropic's page daily.

What the retired waves show, and what Sonnet 4.5 confirmed

Every retirement on the page follows the same shape: a dated deprecation notice with a named replacement, then a retirement day roughly two months later. Opus 4.1 was deprecated on June 5, 2026 and retired on August 5, 2026; Sonnet 4 and Opus 4 were deprecated on April 14, 2026 and retired on June 15, 2026. Sonnet 4.5 followed the pattern to the day: the floor of September 29 passed with nothing announced, and the deprecation notice arrived on September 30, 2026 with retirement on November 30, 2026. A floor tells you when a notice becomes possible; the notice is the date.

What to do

Frequently asked questions

When does Claude Sonnet 4.5 retire?

November 30, 2026. Anthropic's model deprecations page lists claude-sonnet-4-5-20250929 as Deprecated on September 30, 2026 with a retirement date of November 30, 2026 and claude-sonnet-5-5 as the recommended replacement. After the retirement date, requests to the model fail.

What happens when a Claude model is deprecated?

Anthropic's terms: a deprecated model is still functional but no longer recommended, and Anthropic provides a recommended replacement and assigns a retirement date. A retired model is no longer available for use, and requests to models past the retirement date will fail. Anthropic provides at least 60 days' notice before retiring a publicly released model; Sonnet 4.5 got 61.

Are Claude Haiku 4.5 and Opus 4.5 retiring in 2026?

Not by any current announcement. Both are listed as Active with no deprecation date. Haiku 4.5 carries a tentative retirement date of not sooner than October 15, 2026, and Opus 4.5 of not sooner than November 24, 2026. Each is a floor; a retirement would first appear as a deprecation date in the same table with a named replacement, as it did for Sonnet 4.5 on September 30.

Sources

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