An Idiot’s Guide to IR35

Call our best advice team free on mobileWe are open. Call us now on
01925 645 265
Whether you want to ring us, request a callback or chat online with our experts rest assured that no matter how you get in touch, you'll always get the best advice

There’s not long to go until reform to IR35 takes effect. To help get you ready for the changes that are to come, we’ve developed an idiot’s guide to IR35. We demystify all the legislative jargon and get down to the nuts and bolts of the reform.

What is IR35?

IR35 is a piece of anti-tax-avoidance legislation introduced into UK law in 2000. It was a reaction to so-called ‘disguised employment’, this is where a contractor would work through a limited company for tax efficiencies. But in reality, the fundamental relationship between the two parties is that of traditional employment.

IR35 exists to address one crucial question. If there was no intermediary (i.e. the limited company), would the relationship between the end hirer and the contractor be one of employment? IR35 is in place to determine whether the relationship is, or isn’t.

How do I know if I am inside or outside of IR35?

When your assignment is assessed inside IR35, this means that you are a disguised employee and should pay broadly the same tax as a regular PAYE employee. If you are outside IR35, then you are self-employed and can be paid through a limited company, with the tax advantages that come with it.

There are several tests HMRC uses to determine whether you are inside or outside of IR35, which can be summarised as follows:


Have you got control over how you work and what you do, or are you closely managed by your client? A true self-employed person would have control over how to deliver the work.


Would you be able to send somebody else to carry out the work, as and when needed? This would be impossible for an employee, but the right of substitution should be possible for a contractor who is genuinely in business on their own account.

Mutuality of Obligation

Are you under an obligation to accept further work, and is the client under an obligation to continue to offer you work? If so, the assignment has Mutuality of Obligation and, as a result, you could be viewed as an employee in the eyes of HMRC.

Employee benefits

Do you have access to maternity, holiday and sick pay? If so, HMRC will consider you working inside IR35, as you have employee benefits.

Other Factors

There are a number of other factors you should also consider when making an IR35 assessment. For example, whether a contractor is being provided with equipment and whether they are taking any financial risk.

It’s always best to not see IR35 as a tick box exercise but to take a holistic view of the relationship between the contractor and the end hirer.

Upcoming changes

The government delayed IR35 reform to the private sector for 12 months because of the coronavirus but will go live on April 6th, 2021. In short, the changes mean that where they are a medium or large company in the private sector the end-hirer, not the contractor, bears the responsibility and liability for determining whether a contractor is inside or outside of IR35.

There have been some mooted calls for the legislation to be delayed again, however, the legislation received royal assent in August 2020, and it is very unlikely it will be delayed again.

Reforms were introduced to the public sector in April 2017 and the new April 2021 reforms will more closely align the Public and Private sectors. The new reforms will apply to both.


HMRC has the authority to investigate as far back as 20 years if they suspect fraud. If you are found to have been working outside IR35 when the assignment is inside IR35, HMRC may levy a penalty based on several factors. The following are some implications and penalties they could issue:

  • 30% penalty on unpaid tax if, in HMRC’s view, the contractor has been careless
  • 70% penalty on unpaid tax if the contractor was aware they were inside IR35, but didn’t make the payment calculation
  • 100% liable for unpaid tax if the contractor deliberately did not calculate their tax payment in order to hide their underpayment

When reform to IR35 comes into force in April 2021, where the responsibility for assessing IR35 status has shifted, the tax liability will too. Where the end-hirer has failed to take reasonable care the liability for any unpaid taxes will sit with the end-hirer and not the contractor.

Compliance led solutions

Here at Parasol, we have a number of different solutions available. We pride ourselves on being compliance led, which is why we are founding members of the FCSA.

With over 20 years of experience in the umbrella and payroll world, you know with Parasol, you’ll always be on the right side of HMRC. We partner with Qdos to ensure you get fair and accurate IR35 determinations each and every time.

If you would like to find out more, click the request a call back button on the bottom of the page, fill in your information and a member of the team will be in touch.