Blocked Claude requests cost money again, in three areas

Starting today, you'll be billed again for a request if Anthropic's safeguards block it before Claude answers, according to a post from the Claude developer account on X. The charge covers only categories that Anthropic says have low false positive rates: biology, distillation attacks and frontier LLM development.

Anthropic pointed to coordinated attacks on its systems in recent weeks. In a distillation attack, someone pulls large volumes of answers from a model to train their own copy of it. Anthropic didn't say when it stopped charging for blocked requests, how many attacks it saw or what a blocked request will cost.