
What is IR35? And How Off-Payroll Working Rules Work?
IR35, also known as the off-payroll working rules, ensures contractors pay broadly the same tax and National Insurance as employees when their working arrangement mirrors employment. If you would have been an employee without your limited company, IR35 applies. In this guide we’ll explain how IR35 works, who decides your status, and how to reduce risk. What Is IR35? IR35 is UK tax legislation introduced to prevent disguised employment. It applies when a worker supplies services through an intermediary, usually a limited company, but works in the same way as an employee. HMRC looks beyond job titles and focuses on how the work is actually carried out. This is why contractors often seek advice from experienced professionals rather than relying on assumptions or online tools alone. If you are unsure whether your setup qualifies as genuine self-employment, reviewing it alongside a qualified tax advisor is essential. Why IR35 Was Introduced Before IR35, many contractors reduced tax by: HMRC introduced IR35 to create fairness between permanent employees and contractors doing identical work. Today, this affects thousands of contractors across IT, construction, finance, and consultancy. Who the Off-Payroll Rules Apply To You may be affected if you are: IR35 does not apply to sole traders, which is why many self-employed individuals fall under different tax considerations. When IR35 Applies (Public, Private & Small Clients) The responsibility for deciding IR35 depends on the client’s size. This distinction is critical and often misunderstood. Many contractors wrongly assume the client always decides, which is not true when working with small companies. If you are unsure whether your client qualifies as “small”, professional guidance can prevent costly mistakes. Inside IR35 vs Outside IR35 (Key Differences) Feature Inside IR35 Outside IR35 Tax method PAYE Corporation tax NIC Employee & employer None Take-home pay Lower Higher Business risk Minimal Genuine Being inside IR35 can reduce take-home pay by 20–30%, depending on income level. How IR35 Status Is Determined HMRC reviews two things: The Contract Contracts are checked for clauses on: Poorly drafted contracts are a common issue, especially when templates are reused across roles. Actual Working Practices Even a “perfect” contract fails if reality does not match it. Examples HMRC looks at: What Is a Status Determination Statement (SDS)? An SDS explains whether IR35 applies and why. Medium and large clients must: Without a valid SDS, tax liability can shift back to the client. Using the CEST Tool (And Its Limits) HMRC provides the Check Employment Status for Tax (CEST) tool, but it has limitations and relies heavily on how questions are answered. CEST does not account well for complex or hybrid roles, which is why disputes still arise. Working Through an Umbrella Company If you are employed by an umbrella company: However, umbrella arrangements often come with: Before switching, compare this with limited company contracting. How IR35 Works Inside IR35:A contractor works fixed hours, reports to a manager, uses company equipment, and cannot send a substitute. Outside IR35:A contractor delivers project-based work, invoices monthly, uses their own tools, and retains autonomy. These differences are small on paper but decisive in HMRC enquiries. What Happens If IR35 Is Applied Incorrectly? Incorrect IR35 decisions can result in: Contractors often face these issues years later during compliance checks, similar to late-identified tax errors. How Path Accountants Help With IR35 We support contractors and businesses with: The goal is clarity, compliance, and reduced risk. Conclusion IR35 is about how you work, not what you call yourself. Understanding your status before signing a contract protects your income, avoids disputes, and ensures long-term compliance. If you work with UK clients regularly, IR35 should be reviewed as carefully as pricing or contract length. FAQs








