Sonnet 4.5 retires Nov 30, GPT-4o in January

On September 30 Anthropic notified developers that Claude Sonnet 4.5 (claude-sonnet-4-5-20250929) will retire on the Claude API on November 30, 2026. Its recommended replacement is Claude Sonnet 5.5. Anthropic’s documentation is blunt about the effect. “Requests to models past the retirement date will fail.” Amazon Bedrock and Google Cloud set their own retirement schedules for the same models.

OpenAI posted its own notices in October. Its deprecations page lists GPT-4o, GPT-4o mini and GPT-4.1 snapshots for shutdown on January 14, 2027, and several GPT-5 era models for April 1, 2027. Anthropic’s table also shows Claude Haiku 4.5 and Claude Opus 4.5 at or near their earliest possible retirement dates, so more notices may follow.

A model retirement is a change event at the vendor even when the vendor’s product name stays the same. The replacement model can answer differently, cost differently and fail differently.

What this means for your bank

Ask each AI vendor which model IDs its product calls and what its migration date is for any model retiring before April 2027.
Treat a model migration at a critical vendor as a change that needs revalidation of the outputs you rely on.

Sources

Model deprecations (Anthropic)platform.claude.com ↗Deprecations (OpenAI)developers.openai.com ↗

This is for information only and is not legal advice. Retirement dates can change, so verify them against the linked pages before acting.

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