IR35 is the name given to the rules that tax people who are really employees, but operate through their own company to save tax. The idea is that they are taxed the same as employees. The rules never really worked.

Except now they have been made a lot stronger for people in the public sector. Except that those people don't want to pay more tax, and may not cooperate. This could be bad news as some of them are in the health sector.