About IR35 Testing

Trusted expertise to keep you compliant

IR35 Testing was built by ContractorCalculator, the expert guide to contracting, who have 20 years’ experience of the contractor market and have followed IR35 since its inception in 1999. They are also the authors of the recently published book "Beat IR35".

Developed with input from employment law status experts and harnessing self-learning artificial intelligence (AI), the IR35 test itself was first released on ContractorCalculator in 2009 and has already been used by over 100,000 contractors to test their IR35 status.

We have the expertise to make sure your contractors stay fully compliant with IR35, reducing the risk of investigation and tax liabilities as a result.

Our team combines more than 30 years of software development experience with know-how in crucial areas such as employment case law. This unique blend of expertise enables us to deliver an IR35 evaluation equivalent to that of an employment lawyer in under one second.

And with our network of established IR35 experts and tax insurers for you to choose from, you’re dealing with a compliance solution that offers complete protection.

The expert guide to contracting

ContractorCalculator was originally created in 1999 to help contractors navigate the IR35 tax legislation. It then evolved into a multifaceted resource hub and is now the UK’s leading website for the contingent workforce, attracting over 150,000 visitors per month.

As well as a comprehensive range of free online financial, salary and tax calculators, we also provide expert industry commentary and analysis from our network of tax and industry leaders.

Keeping our finger on the pulse of the contracting sector has helped us to develop in-depth knowledge of IR35, which we harnessed to create this comprehensive compliancy tool.

Contractor Calculator
over 25,000 passes

Used by over 100,000 contractors

over 20 years

Over 20 years software development experience

since 2009

Built in 2009 and continuosly refined to align with latest IR35 legislation


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