10/04/2026
IR35 is a UK tax rule designed to determine whether a contractor working through a limited company should be treated as self-employed or as an employee for tax purposes. It focuses on the actual working relationship rather than just the contract, meaning factors such as control, substitution, and mutual obligations are key in deciding status.
If you are inside IR35, your income is taxed through PAYE with Income Tax and National Insurance, significantly reducing take-home pay and limiting the use of dividends. If you are outside IR35, you are treated as genuinely self-employed, allowing greater flexibility, tax efficiency, and the ability to claim business expenses. Responsibility for determining IR35 status depends on the client’s size, with medium and large businesses issuing a Status Determination Statement, while contractors working with small companies must assess their own status.
Getting this wrong can lead to underpaid tax, penalties, and financial risk, making it essential for contractors to review their contracts and working practices carefully to ensure compliance and protect their income.