Upload your contract and get an instant IR35 risk assessment across control, substitution and mutuality of obligation—plus practical fixes you can apply today.
IR35 looks at the working relationship, not just the wording. Our checker analyses the factors used by HMRC to decide employment status for tax:
Who decides how, when and where the work is done. Strong client control points to “inside IR35”.
Is there a genuine, unfettered right to send a suitably qualified substitute? Approval requirements carry less weight.
Is the client obliged to offer work and contractor obliged to accept? Lack of ongoing obligation supports “outside IR35”.
Who bears costs, provides equipment, and fixes defects at their own expense?
Multiple clients, marketing, professional insurances, and other indicators of independent business.
Who decides how, when and where the work is done. Strong client control points to “inside IR35”.
Key factors that influence your IR35 status determination
See what your report will look like
Analyzed in 23 seconds
“Company may process Customer data for any business purpose…”
Risk: Violates GDPR Article 6 – lacks lawful basis and purpose limitation
Suggestion: Add “solely for providing the Services and in accordance with Customer instructions”
“Either party may terminate with 7 days notice…”
Risk: Too short for business continuity planning
Suggestion: Negotiate 30 days minimum with data export provisions
Common questions about off-payroll working rules
UK rules that determine whether a worker is employed or self-employed for tax when supplying services via an intermediary (e.g., a limited company).
Public sector & medium/large private sector: the client decides and must issue an SDS.
Small private-sector clients: the contractor decides.
No. Our checker gives best-practice risk guidance and suggested wording. CEST is HMRC’s questionnaire producing HMRC’s view based on your answers (last updated 30 April 2025). Many users use both.
If the client is “small” (Companies Act thresholds), the contractor remains responsible for IR35. Check thresholds before the tax year; group structures matter.
No. Files are processed transiently for analysis and not stored permanently.
Use it as internal evidence of reasonable care and to improve contracts/practices. Always align the actual working practices with the contract and seek advice on edge cases.
Average time to first result: 20–60 seconds
© 2025 IR35 Contract Checker. This tool provides guidance only and is not tax or legal advice.
Updated January 2025 • HMRC CEST last updated 30 April 2025