endoflife.ai
Claude models Accuracy API

Claude Sonnet 4.5 Is Not Retiring on September 29, 2026. Here Is Why

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

Claude Sonnet 4.5 has no retirement date. Anthropic's model deprecations page lists claude-sonnet-4-5-20250929 as Active, with no deprecation date and a tentative retirement date of not sooner than September 29, 2026. That phrase is a floor: the earliest day Anthropic allows itself to retire the model, one year after its release on September 29, 2025. It is not an announcement that anything happens on that day. The same is true of Haiku 4.5 (not sooner than October 15, 2026) and Opus 4.5 (not sooner than November 24, 2026), and every other Active model on the page carries a floor in 2027.

A correction to our own data. Until today endoflife.ai served each of those floors as the model's end-of-life date, which is how the upstream dataset records them; the Sonnet 4.5 page was counting down to September 29. That was wrong. As of this build the Active models are served as supported with no announced end date, with Anthropic's page as the recorded source, and the date returns only when Anthropic publishes a deprecation with a real retirement day.
Quick answer: Claude (Anthropic) Claude Opus 5.5 is supported, with no end-of-life or end-of-support date announced yet. 19 of 33 tracked Claude (Anthropic) versions are past end of life; the most recent to reach it, Claude Opus 4.1, did so on August 5, 2026. 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.

Put together: a model cannot retire on its floor date unless Anthropic has first moved it to Deprecated, named a replacement and given at least 60 days' notice. None of that has happened for Sonnet 4.5, Haiku 4.5 or Opus 4.5.

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.

Free · No obligation · Independent — we track the dates, vendors don’t pay for placement · dates verified against vendor sources. See all support options →

What the table says, model by model

API model nameReleasedStateDeprecatedRetirement
claude-sonnet-4-5-202509292025-09-29ActiveNoneNot sooner than September 29, 2026 (floor)
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 started failing. For the three Active models the last column is Anthropic's floor, printed as text because it is not a date in our data. The retired rows are served from data and re-read from Anthropic's page daily.

What the retired waves show

Every retirement on the page so far followed the same shape: a dated deprecation notice with a named replacement, then a retirement day roughly two months later in the 2026 waves. 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. None of them retired on a floor date; each got its own dated announcement first. That is the signal to watch for Sonnet 4.5: a date appearing in the Deprecated column, not the floor passing.

What to do

Frequently asked questions

When does Claude Sonnet 4.5 retire?

No retirement date has been set. Anthropic's model table lists claude-sonnet-4-5-20250929 as Active, with no deprecation date and a tentative retirement date of not sooner than September 29, 2026. That is the earliest day Anthropic allows itself to retire the model, not an announcement that it will. Retirement only follows a deprecation, and Anthropic provides at least 60 days' notice before retiring a publicly released model.

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. In the 2026 waves so far, the gap between the deprecation notice and the retirement day was roughly two months.

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.

Sources

Related