Deprecation of fine tuned models, but still can't access newer ones?

Hello,

You’re not misreading the shutdown notice: fine-tuned versions of gpt-4.1-nano-2025-04-14 are scheduled to be removed on October 23, 2026, and the deprecations page lists gpt-5-nano as the recommended substitute.

The “substitute model” column is a migration target for using the API after shutdown; it does not currently mean that gpt-5-nano is available for fine-tuning. Fine-tuning itself is not being removed, but GPT-5-family models are not currently listed in the public fine-tuning docs as supported fine-tuning base models.

If you need a fine-tuned replacement today, please use one of the currently supported fine-tuning models documented in the fine-tuning guides. If your goal is specifically to migrate from a fine-tuned gpt-4.1-nano model, we recommend evaluating base gpt-5-nano against your existing evals/prompts, since that is the documented substitute for that deprecated model family.

Reference:

• Deprecation page: developers.openai.com/api/docs/deprecations
• SFT docs: supervised fine-tuning
• DPO docs: direct preference optimization
• RFT docs: reinforcement fine-tuning