introducing-claude-fable-5-and-claude-mythos-5 changedmodels/fable-5/introducing-claude-fable-5-and-claude-mythos-5
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24 Aug 2026
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Recorded edits9to this page, all time
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4848
4949### Billing
5050
51You are not billed for a request that is refused before any output is generated. When you retry on another model, [fallback credit](https://platform.claude.com/docs/en/build-with-claude/fallback-credit) refunds the prompt-cache cost of switching, so you avoid paying that cost twice.
51A refusal that arrives before any output is billed when it is in a category with low volumes of false positives, to disrupt attempts to circumvent Anthropic's safeguards at scale. Before September 24, 2026, these refusals were not billed. A mid-stream refusal bills the input tokens and the output already streamed at normal rates. For the billed categories, see [How refusals are billed](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#how-refusals-are-billed). When you retry on another model, [fallback credit](https://platform.claude.com/docs/en/build-with-claude/fallback-credit) refunds the prompt-cache cost of switching, so you avoid paying that cost twice.
5252
5353## Availability
5454
No line in this hunk matches that.