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Demystifying IR35 Tax: Understanding the UK's Off-Payroll Working Rules

Let's talk boring but necessary accounting.

No frills, heirs or graces.

Just plain old accounting terminology.

But let's bust some jargon and do some explaining in the meantime.

And the subject matter is IR35.

Introduced by the UK's HM Revenue and Customs (HMRC), the term 'IR35' might sound like technical jargon, but its implications for contractors and businesses in the UK are profound. This legislation aims to tackle what HMRC terms "disguised employment". But what does this mean, and how might it impact you? Let's break it down.

What is IR35?

IR35 refers to the UK's Intermediaries Legislation, a set of tax laws focusing on identifying individuals who are essentially 'disguised' employees to avoid paying the corresponding taxes and National Insurance contributions. In simpler terms, it's about ensuring that contractors who work similarly to full-time employees pay the same taxes as employees.

Why was IR35 introduced?

IR35 was implemented in 2000 to address the situation where workers act as contractors to gain tax advantages, even if they function similarly to regular employees. This approach often reduced tax liability for both the worker and the hiring company.

Inside vs. Outside IR35:

  • Inside IR35: If a contractor's working arrangement is similar to that of an employee, they're considered "inside IR35". This means they must pay the same tax and National Insurance contributions as regular employees.

  • Outside IR35: If a contractor is deemed to be genuinely self-employed, their contract falls "outside IR35". They can be paid gross and handle their own taxes.

Factors Determining IR35 Status:

1. Control: Does the client have control over how, when, and where the contractor works?

2. Substitution: Can the contractor send someone else in their place?

3. Mutuality of Obligation (MOO): Is the client obligated to offer work, and is the contractor obligated to accept it?

Changes from April 2021:

Previously, it was the responsibility of the contractor's intermediary (usually their limited company) to determine their IR35 status. However, as of April 2021, in the private sector, this responsibility shifted to the end client (the company hiring the contractor). This change was already in place for the public sector since 2017.


1. For Contractors: Being deemed "inside IR35" might mean a reduction in net income due to increased tax liabilities.

2. For Employers: There's now an added administrative burden to determine the IR35 status of contractors. Incorrect determinations can lead to back taxes and fines.

IR35 legislation underscores the importance of clarity in working relationships. Both businesses and contractors should seek expert advice to ensure they correctly understand and apply the rules, minimising financial and legal risks.

Remember, while this blog offers a general overview, IR35 is complex and continually evolving. It's essential to consult with tax professionals or legal counsel to navigate its intricacies effectively.


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