# Anthropic Claude Sonnet 4.5 — deprecation status

> No — Claude Sonnet 4.5 is not deprecated as of July 30, 2026. Anthropic has not deprecated it, but publishes September 29, 2026 (in 61 days) as the earliest date it could be retired.

The September 2025 Sonnet, still active but with the second-nearest earliest retirement date of any live Anthropic model. It is the last Sonnet to use explicit extended thinking rather than the adaptive thinking introduced in 4.6.

## Facts

| Field | Value |
| --- | --- |
| Provider | Anthropic |
| Model id | `claude-sonnet-4-5-20250929` |
| Status | Active |
| Aliases | `claude-sonnet-4-5` |
| Released | September 29, 2025 |
| Shutdown (earliest) | September 29, 2026 (in 61 days) |
| Last verified | July 30, 2026 |

## FAQ

### When will Anthropic Claude Sonnet 4.5 shut down?

Anthropic Claude Sonnet 4.5 is scheduled to shut down on September 29, 2026, in 61 days. Anthropic publishes this as the earliest possible retirement date rather than a firm commitment, so it may move later — but not earlier.

### Is Anthropic Claude Sonnet 4.5 still available?

Yes. Anthropic Claude Sonnet 4.5 is active and fully supported as of July 30, 2026.

### Does this apply to claude-sonnet-4-5 too?

Yes. Anthropic Claude Sonnet 4.5 is also published as `claude-sonnet-4-5`; that id shares the same lifecycle dates as `claude-sonnet-4-5-20250929`.

## Sources

- [Anthropic model deprecations](https://platform.claude.com/docs/en/about-claude/model-deprecations) — accessed 2026-07-30

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Canonical page: https://modeldeprecations.dev/anthropic/claude-sonnet-4-5-20250929
JSON: https://modeldeprecations.dev/api/v1/models/anthropic/claude-sonnet-4-5-20250929.json