I recently left a school, and they have asked me back for supply. I expected to be on their PAYE to be honest, but after my first day of supply, I was asked to invoice them. Do I need to be a limited company to do this? As much as I want to work in a school where I know my way around, I can't really face the hassle of this and might just go through an agency instead. I can am only doing one day a week (if that) as some extra cash to help with a career change. Thanks in advance for any advice.