IR35 Status Checker
Answer 12 questions about your working arrangement to get an indicative IR35 assessment. Based on the three key tests HMRC uses: control, substitution, and mutuality of obligation.
Indicative assessment only · Not a substitute for professional advice
Substitution
Can you send someone else to do the work? This is the single most important factor.
Could you send a substitute to do the work?
Do you have a genuine, contractual right to send someone else in your place? Have you ever done so, or could you realistically?
High importance factor
If you sent a substitute, who would pay them?
Would you pay the substitute from your own fees, or would the client pay them directly?
High importance factor
Control
Does the client control how, when, and where you work?
Do you decide how the work is done?
Can the client tell you exactly how to perform your tasks, or do they just specify the end result?
Do you decide when you work?
Are you free to set your own hours, or does the client require you to work specific hours?
Do you decide where you work?
Can you work from anywhere, or must you be at the client's premises?
Can the client move you to different tasks?
Can the client reassign you to different work, or are you engaged for a specific project/deliverable?
Do you provide your own equipment?
Do you use your own laptop, software, tools — or does the client provide everything?
Are you part of the client's organisation?
Do you attend their all-hands, use their email, appear on their org chart, have a staff badge, get invited to socials?
Mutuality of Obligation
Is there an ongoing obligation between you and the client?
Is the client obliged to offer you work?
Must the client provide you with work for the duration of the contract, or can they end it when a project finishes?
Are you obliged to accept work offered?
If the client offers you additional work or extends the contract, must you accept?
Do you bear financial risk?
Could you make a loss? E.g., fixed-price work where you underestimate effort, costs you bear yourself, rectifying defective work at your own cost.
Do you work for other clients simultaneously?
Are you free to (and do you) work for other clients at the same time?
How long have you been on this contract?
Longer engagements with the same client increase IR35 risk, even if the contract is renewed separately.
What to do next
Check with HMRC's CEST tool — the official Check Employment Status for Tax tool at gov.uk. It's not perfect, but HMRC will stand by its result if you provide accurate answers.
Review your contract — ensure it reflects the reality of how you work, not just what sounds good. HMRC looks at practice over paperwork.
Consider IR35 insurance — policies typically cost £200-500/year and cover legal defence costs and potential tax liabilities if investigated.
Important disclaimer
- This is an indicative assessment only — not legal or tax advice.
- IR35 is determined by the overall picture, not any single factor. Courts weigh substitution particularly heavily.
- Since April 2021, medium and large private sector clients determine your status under the off-payroll working rules.
- HMRC's CEST tool is the official assessment — use it alongside this tool for a more complete picture.
- If you're borderline, a specialist IR35 advisor (typically £200-400 for a contract review) is well worth the investment.
Understanding IR35
IR35 is tax legislation designed to combat “disguised employment” — where someone works like an employee but operates through a limited company or other intermediary to pay less tax. If your contract is caught by IR35, you're taxed as if you were an employee.
The three key tests
Courts and HMRC look at three main factors when determining employment status:
- Control: Does the client control how, when, and where you work? More control = more likely inside IR35.
- Substitution: Can you send someone else to do the work? A genuine right of substitution is a strong indicator of being outside IR35.
- Mutuality of obligation: Is the client obliged to offer work, and are you obliged to accept it? Ongoing mutual obligations point towards employment.
Off-payroll working rules (April 2021)
Since April 2021, medium and large private sector clients (and all public sector clients since 2017) are responsible for determining your IR35 status. They must provide a Status Determination Statement (SDS). Small private sector clients still leave the determination to the contractor.
What happens if you're inside IR35?
If inside IR35, the fee-payer (usually your agency or client) deducts income tax and employee NICs from your payments. You lose the tax efficiency of taking dividends. The tax difference can be significant — often several thousand pounds per year.
This assessment is for guidance only. IR35 determinations depend on the full facts of your engagement and can only be definitively decided by a court or tribunal. Always seek professional advice if unsure.