Blocking bring your own Copilot on work documents is something more organisations should be looking at. Microsoft allows multiple account access by default unless you explicitly block it, which means employees may be able to use personal Copilot entitlements on work files in supported Microsoft 365 apps. This post explains what BYOC is, why it matters, what Microsoft allows by default, what the risks look like, and how to block it if it does not fit your governance model.