IR35 status is not determined by job title, industry, or day rate. It comes down to the reality of how you work on a specific engagement. HMRC and tribunals apply three primary tests, along with several secondary factors, to decide whether a contractor is genuinely self-employed or effectively an employee.
1. Right of substitution
Can someone else do the work in your place? If you have a genuine, unfettered right to send a qualified substitute to perform the work, this strongly indicates self-employment. The substitute must be someone you choose and pay from your own pocket, not someone the client selects from their own pool. A purely theoretical right written into a contract but never exercised carries less weight than a substitution clause that has actually been tested.
2. Control
Does the client control what you do, how you do it, and when you do it? Employees are typically told how to perform their work, what hours to keep, and which processes to follow. Genuine contractors decide their own methods, bring their own expertise, and are engaged for their output rather than their time. If the client dictates your working hours, supervises your methods closely, or requires you to attend mandatory meetings that serve no project purpose, these are indicators of employment.
3. Mutuality of obligation (MOO)
Is the client obliged to offer you work, and are you obliged to accept it? In employment, there is a continuous obligation on both sides. In contracting, you deliver a defined scope of work and either party can walk away at the end of the engagement without further obligation. If you are offered work on a rolling basis with an expectation that you will always accept, this looks more like employment.
Secondary factors
Beyond the three core tests, tribunals also consider financial risk (do you invest your own money in equipment or training?), whether you provide your own tools, integration into the client organisation, the intention of the parties, and whether you have multiple clients. No single factor is decisive. It is the overall picture that matters.
Practical advice
Review your working arrangements honestly before accepting a contract. If you are genuinely running a business, making your own decisions, and bearing financial risk, you are in a strong position. If you are told where to sit, what hours to work, and are managed day-to-day like a permanent team member, the engagement is likely inside IR35 regardless of what the paperwork says.