2025/26 All tools updated for the current UK tax year — VAT threshold £90,000 · Personal allowance £12,570
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IR35 Status Checker 2025/26

Answer questions about your contract and working practices to get an indication of whether your engagement is likely inside or outside IR35. This tool covers the three key IR35 tests used by HMRC and the courts.

Answer all questions based on the reality of your working arrangement — not just what your contract says. HMRC looks at actual working practices, not just written terms.

IR35 Assessment

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Important: This tool provides an indication only. IR35 status depends on the full facts of each engagement and is ultimately determined by HMRC or a tribunal. Always seek professional advice for a definitive assessment.

For guidance only. TheBizHQ.com is a private, independent website — not affiliated with HMRC, Companies House or any UK government body. All figures are estimates based on the information you enter and should not be relied upon for financial, tax or legal decisions. Tax rates are reviewed periodically but may not always reflect the latest HMRC changes. Full disclaimer →

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What is IR35?

IR35 (also known as the off-payroll working rules) is tax legislation designed to ensure that contractors who work like employees pay broadly the same tax as employees. It applies when a contractor provides services through an intermediary — typically a personal service company (PSC) — but would be considered an employee if they worked directly for the client.

The three key IR35 tests

IR35 status is determined primarily by three tests established in case law:

  • Substitution — if you have a genuine right to send someone else to do the work and the client must accept them, this points strongly towards being outside IR35. A substitution clause in your contract means little if it has never been exercised or would never be accepted in practice.
  • Control — if the client controls how, when and where you work, this points towards inside IR35. Outside IR35 contractors typically control their own working methods and hours.
  • Mutuality of obligation — if the client is not obliged to offer work and you are not obliged to accept it, this points outside IR35. A rolling contract with an expectation of continued work creates mutuality of obligation.

Who determines IR35 status?

Since April 2021 (and April 2017 for the public sector), medium and large private sector clients are responsible for determining the IR35 status of their contractors. For small companies (two of: turnover under £10.2m, balance sheet under £5.1m, fewer than 50 employees) the contractor's own PSC is still responsible for the determination.

What happens if you are inside IR35?

If your engagement is inside IR35 you pay income tax and National Insurance as if you were an employee — but without employee benefits such as holiday pay, sick pay or pension contributions. This significantly increases your tax bill and is often referred to as the IR35 penalty.

CEST tool

HMRC provides its own Check Employment Status for Tax (CEST) tool at gov.uk. HMRC will stand by the result of CEST if the information entered is accurate and the tool is used correctly. However many tax professionals consider CEST to be unreliable in borderline cases.

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