IR35

UK tax legislation that determines whether a contractor working through a limited company should be taxed as an employee rather than a self-employed person.

IR35 affects both contractors and businesses hiring them. Getting it wrong can result in significant tax bills and penalties. Any contractor doing ongoing, supervised work for one client is at risk.

You hire a developer through their limited company. They work exclusively for you, follow your hours, and use your equipment. HMRC may deem this employment (inside IR35), making you liable for their PAYE and NI.