The ultimate IR35 compliance solution

We are the most comprehensive IR35 compliance solution available to hirers and contractors, delivering fast and accurate online assessments and IR35 support services.

  • Contractors – achieve IR35-free contracting with minimum hassle
  • Agencies / accountants – minimise risk and admin compliance overheads
  • Service providers – Sell solutions to thousands of contractors

Who are you?


  • Get and stay outside IR35
  • Achieve tax savings worth thousands
  • Take the test in 15 minutes
  • Prove your status with a report and certificate


  • Ensure your contractors are tested for IR35
  • Reduce your risk and compliance costs
  • Demonstrate due diligence to HMRC
  • Deliver added value services at no extra cost


  • Sell IR35 reviews and tax insurance
  • Boost revenues and grow your client base
  • Sell directly to contractors
  • Gain additional promotion via our PSL

Our IR35 assurance process

IR35 Testing Flowchart

IR35 Testing:

  • Helps contractors stay outside IR35
  • Keeps agencies tax compliant
  • Minimises compliance risk
  • Reduces HMRC investigation costs
  • Includes insurance options for peace of mind

Key features of our IR35 test:

  • Built in 2009, used by over 100,000 contractors
  • Developed by IT, IR35 and employment law experts
  • Encompasses 17 years of IR35 knowledge
  • Delivers IR35 pass certificate
  • Provides expert advice to avoid IR35
  • 28 page IR35 Test Report - click to see sample

Who are we?

IR35 Testing

17 years of serving the UK’s contracting community

IR35 Testing is brought to you by ContractorCalculator, the UK’s leading contractor brand and website for contingent workers, with circa 100,000 visitors per month.

Originally created in 1999 to help contractors navigate IR35, ContractorCalculator has evolved into a vital resource hub, offering a range of free online financial and tax calculators, as well as expert commentary from industry leaders.

We also publish the contracting industry bible, the Contractors’ Handbook, and offer financial services to contractors via ccFinancials.

More about us