Not much other than corporate policy and Anthropic's policy that you are not allowed to do that unless your company is very small.

Anecdotally, I know that quite a number of people at my company (mid-sized, ~5000 employees) have personal ChatGPT or Anthropic subscriptions they are using. Despite the fact that we have Microsoft Copilot (the web version) for everyone, and Github Copilot (the CLI thing) with low limits (500-1900 credits/month) for people who can justify it. But Copilot isn't all that great compared to Claude Code, so a lot of people continue to use their personal account.

It violates a number of policies and is probably a firing offense, but I haven't heard of anyone getting nailed for it yet. And I know that line managers are aware of it happening.

I do wish they'd just let us buy Claude Code API access. Copilot w/Opus 5.5 is noticably worse than CC using the same model. But oh well, I'm not getting fired over it.