They do, yes. Many public sector companies (inc HMRC) are now forcing contractors to be paid by PAYE even. Generally though, you're safe as long as you work at

They do, yes. Many public sector companies (inc HMRC) are now forcing contractors to be paid by PAYE even. Generally though, you're safe as long as you work at the same company for less than 24 months. Then you need to find a new contract or relocate (working at a different physical office or taking on multiple clients can get around IR35 (if you fall within IR35 you're considered to be a disguised employee, not an independent contractor, and must pay higher income tax).