The off-payroll rules changed in 2021. Most IR35 guides online predate that change, or gloss over the practical bits.
So I built a checker.
What changed in 2021
Before April 2021, contractors determined their own IR35 status. Now, for medium and large private sector clients, the client determines it — and is liable if they get it wrong.
Small clients (under 2 of: £10.2m turnover, £5.1m assets, 50 employees) still use the old rules. But most contractors work with medium/large companies eventually.
The 3 tests that actually matter
1. Substitution — Can you send someone else to do the work? A genuine right of substitution points outside IR35. A clause in a contract that says you can but in practice you never would? HMRC sees through that.
2. Control — Does the client dictate when, where, and how you work? If you're told to be in the office 9-5, use their equipment, and follow their processes... that looks like employment.
3. Mutuality of obligation — Is the client obliged to offer work and are you obliged to accept it? Zero obligation on both sides = outside IR35.
What the checker does
Runs through 12 questions covering the main tests. Gives you an indicative result with a plain-English explanation of which factors pushed the outcome.
Free, no login: landolio.com/tools/ir35-checker
The honest caveat
It's indicative, not legal advice. IR35 is fact-specific and a borderline case needs a proper contract review. But for a quick sanity check before starting a new contract, it's useful.
If you need the full picture
The Contractor Compliance Pack (£9) includes:
- IR35 status worksheet
- Contract red flags checklist
- Letter template for challenging an inside-IR35 determination
- CEST tool walkthrough guide
Are you currently inside or outside IR35? What has been your experience with client-side determinations?
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