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IR35 guides for contractors.
Plain-English explanations of the rules, the case law and the contract clauses that decide IR35 risk — updated for the 2026/27 tax year.
IR35 small company thresholds for 2026/27: what changed and who it affectsThe IR35 small company thresholds rose to £15m turnover and £7.5m balance sheet. Here's how the test works, when it applies, and what it means if your client is now small.Who decides your IR35 status — you or your client?Whether you or your client decides IR35 status depends on the client's size and sector. Here's how Chapter 8 and the off-payroll rules work, and who pays if it's wrong.How to challenge an IR35 Status Determination StatementDisagree with an inside-IR35 SDS? How the client-led disagreement process works, the 45-day deadline, what to put in your challenge and what happens next.The IR35 substitution clause: what makes it countA genuine right of substitution is one of the strongest outside-IR35 indicators — but only if it's real. Example wording, red flags and how to strengthen your clause.Mutuality of obligation after PGMOL: what the Supreme Court changedThe Supreme Court's 2024 PGMOL judgment held that mutual obligations within a single engagement can be enough. What that means for 'no MOO' arguments and your IR35 contract.The IR35 control test: what counts as controlControl is often the deciding IR35 factor. How tribunals assess control over what, how, when and where you work, what PGMOL changed, and clauses to watch.IR35 contract checklist: 10 clauses to check before you signA practical IR35 contract review checklist for contractors: the ten clauses that most affect your status, what good looks like and the red flags to push back on.How much does an IR35 contract review cost?IR35 contract review costs in 2026: free tools, AI reports and specialist reviews compared on price, turnaround and what you get — and how to choose.The IR35 part and parcel test: are you treated like staff?Being 'part and parcel' of the client's organisation points towards employment. The everyday signs tribunals and HMRC look for, and how to keep a clear line as a contractor.The IR35 hypothetical contract, explainedIR35 asks what your contract would look like if you'd been engaged directly by the client. How the hypothetical contract is built, what Atholl House changed and why the agency paperwork isn't the whole story.
Check your own contract
Upload your contract and answer 12 questions. You'll get a clause-by-clause IR35 risk report with suggested wording — usually in 1–3 minutes, for £9.