Inside or outside IR35, with the case law that says so.

IR35 questions, answered

Tap any question to expand. Contracting in a specific field? See how IR35 plays out by role, or read the full IR35 guide.

Is my IR35 result legally binding?

No — and neither is any other tool's, including HMRC's own CEST. IR35 is built on UK case law, so status is ultimately tested by the facts of how you actually work, not by any one tool's verdict.

What Nebula gives you is your reasoning and the case law we referenced: your result, your factor-by-factor reasoning, and the tribunal precedents we drew on — the kind of evidence HMRC asks to see if your status is ever challenged. Borderline results are clearly flagged with a recommendation to have a qualified IR35 specialist review them before you act on them. Nebula is not your tax or legal advisor; you remain responsible for taking reasonable care over your status.

What is Nebula IR35?

Nebula IR35 is a free way to check whether your contract is inside or outside IR35 — the rules that decide whether HMRC taxes you like an employee. You answer a few plain questions and get a clear verdict in minutes, plus how sure we are. If it's a close call, we flag it and recommend you have a qualified IR35 specialist review it before you rely on it. Need it in writing? A £9.99 report reads your actual contract and gives you a signed IR35 Status Assessment.

How do I know if I'm inside or outside IR35?

It comes down to how you actually work, not just what your contract says. We look at the same five things HMRC does: whether you could send someone else to do the work, who controls how and when you do it, whether you have to be given work and have to accept it, whether your own money is at risk, and whether you run like a genuine business. The free check weighs all five and gives you a verdict in minutes.

Is the IR35 status check really free?

Yes, really. Your verdict, how confident we are, and a preview of the reasoning are free — no card and no sign-up. If you want the full write-up, with your actual contract analysed and a signed status assessment you can share, that's £9.99.

Does Nebula produce a Status Determination Statement (SDS)?

No — and no tool can. Under s.61NA ITEPA 2003 an SDS is issued by the end client, where the off-payroll rules apply because the client is medium or large or a public authority. A worker cannot issue themselves one. What we produce is your own IR35 Status Assessment: a signed, dated statement of your status and the reasons for it, to hand to your client, agency or accountant. If your client is small, that is your evidence of reasonable care under Chapter 8 and the determination really is yours — provided your own company is not a managed service company, since the MSC legislation takes precedence over Chapter 8 (ESM10004). If your client is medium or large, it is material for making representations; the determination stays theirs.

How is this different from HMRC's CEST tool?

CEST does not always reach an answer: HMRC's own published usage data records it returning a determination in 80% of uses between 25 November 2019 and 31 January 2020, leaving the rest undetermined. It also does not put explicit mutuality questions — the factor the Supreme Court addressed in the 2024 PGMOL ruling. Nebula weighs all five factors, including mutuality, and shows you the reasoning; if your case is genuinely on the line we flag it and recommend a qualified IR35 specialist. One thing CEST has that we do not: HMRC says it will stand by a CEST result where your information is accurate and in line with its guidance. That backing is CEST's alone — it does not extend to Nebula or any other third-party tool. Plenty of contractors run both.

What happens if HMRC challenges my IR35 status?

Your paid report includes a dated IR35 Status Assessment with the five-factor reasoning and the tribunal precedents we relied on — the same evidence trail a tax adviser would put together. If HMRC opens an enquiry, you can hand it to your accountant or IR35 defence provider. We do not currently bundle tax-investigation insurance; if you want cover, specialist IR35 insurers sell it as a separate policy.

How much does this cost compared to other IR35 providers?

The free five-factor check has no equivalent in the market. Specialist IR35 contract reviews elsewhere typically run £50–£130+VAT. Our £9.99 paid report reads your actual contract, produces a signed status assessment, and clearly flags borderline cases with a recommendation to seek a qualified IR35 specialist's review. We do not include tax-investigation insurance at this price — if you need that, look at standalone IR35-investigation insurers.