Contractors IR35

How to build an impenetrable IR35 defence

Read on below for a guest post from Mindful Contract Solutions A great contract is an invaluable asset for an…

Kingsbridge by Kingsbridge
Contractor working on a laptop

Read on below for a guest post from Mindful Contract Solutions

A great contract is an invaluable asset for an IR35 defence, helping to effectively show that an engagement points to being outside IR35. Should an IR35 tribunal occur, having a great contract will put a contractor in a strong position to protect an outside IR35 determination. An IR35 tribunal decision is oftentimes weighted heavily on a contractor’s working practices, wherein lies the biggest reason why such cases can take years to resolve.

In this post, we will cover a few key working practices that, when coupled with a safe and strong contract, will bolster your IR35 defence significantly.

Right to Substitution in practice

Whilst most clients do not hesitate to offer contractors a right to substitute, the arrangement can often be more of a written gesture without any intention of acting on the clause. A contractor’s right to substitution should be clearly stated in their contract, and the fee-payer or end client should be aware of this and happy for the contractor to use it in practice, which having included in your contract can definitely help in the event of a tribunal.

Honouring a contractor’s right to substitution may stand up as good evidence alone for ‘Small Consultancy’ Limited, but it may not cut the mustard for ‘Large Corp’ Limited. Courts would expect an end client to have a proper process in place, so they know what to do in the event of a substitution.

Statement of Work – do you really mean it?

One of the most popular IR35 defence tactics employed by end clients and intermediaries is the Statement of Work, or SoW. This is a written specification of activities (also called scope of services) that the contractor is required to perform in order to deliver a piece of work.

Theoretically, at least, if there is a SoW at the point of agreeing a contract, the “scope of services” guides their work – i.e. the client isn’t the one directly supervising, controlling or directing the work, and therefore the contractor is managing themselves within the parameters of the agreed spec.

When a SoW is used in large commercial contracts with IT systems integrators (SI), the client should consider that the risk of non-delivery within the funding envelope sits with the SI. It’s very unlikely that clients doing SoWs with one-man-band contractors would hold them to a similar account.

For one, contractors (as opposed to freelancers) tend to have only one active income stream at any point in time. They can of course take some risk on some part of it but it would be commercially unfeasible for them to take a risk of non-delivery on all of it.

In the end, it’s all about control

Client control is one of the most important IR35 tests. The perennial problem has been that clients take too much control over how, where, and when the work is done, and ultimately treat the contractor like one of their employees. To be on the right side of IR35, contractors should be managing their own day – as long as they’re meeting project objectives on time, it’s entirely up to them how they do so.

Here’s where a credible intermediary can come into play. An intermediary that focuses on specific types of work, and has some capacity to understand the technology in play, can stand in as a Managed Service Provider. They can give clients the confidence to let go of control, and in turn will act responsibly on behalf of the clients in dealings with contractors, be it on matters concerning recruitment, or dealing with performance concerns.

A commercially-savvy intermediary will also shift you from day rate-based contractor arrangements to true risk-adjusted fixed price options. They will also help deploy fit-for-purpose working practices to support substitution, meaning, if necessary, you can stand and talk at length in that witness box of the things you did to make substitutions happen.

Where do you go from here?

Hopefully you already have a strong contract ready to go, and paired with sound working practices that follow the rules set out in your contract, you should be prepared in the event of an IR35 tribunal.

If your contract and working practices don’t quite match up, one option you could consider is a credible intermediary, acting as a one-stop-shop, they will employ a range of all such measures, and more, to make sure you get to the right side of IR35 and stay there.

This post was written by Amit Kapoor, Director of Mindful Contract Solutions. Acting as an MSP on digital transformation programmes, Mindful have delivered over £13m worth of outside-IR35 services in the new off-payroll regime to the public sector.

Related topics

Contractors IR35

You might also like...

Back to resources
Close up photo of female worker at a desk with laptop and calculator, representing article on what insurance contractors need
Contractor Guides Contractors 03 Nov 2026

What insurance contractors need?

We know it can be a minefield for contractors when it comes to purchasing the right contractor insurance to protect…

Image of a handheld drill on a work bench, representing guide on how to insure work tools for tradespeople
Trades Trades Life 09 Sep 2026

How to insure your tools: a tradesperson’s guide

Most tradespeople spend a lot of time thinking about the next job, the next customer, or the next challenge on…

A flat lay of a desk with stationery and notebook with writing 'insurance checklist', representing guide on questions to ask when buying contractor insurance
Contractor Guides Contractors 24 Aug 2026

7 things to ask before buying contractor insurance

Buying contractor insurance isn’t exactly the most exciting item on your to-do list.  When you’re focused on winning contracts, meeting…

Image of tradesman leaning against white van looking at insurance quotes on his phone, representing article discussing cheap tradesmen insurance
Trades Trades Life 28 Jul 2026

Cheap trades insurance: how low is too low?

When you’re running your own trades business, it’s only natural to try and keep costs to a minimum. But for…

Photo of protest crowd in london, representing article on loan charge review scandal
Contractors News 15 Jul 2026

Why the Loan Charge scandal isn’t going away

In the late 1990s, loan-based remuneration schemes began to emerge before becoming widespread among contractors and freelancers during the 2000s.…

Image of tradesman's arm being bandaged, representing article on employers' liability insurance for tradespeople
Trades Trades Life 07 Jul 2026

Do tradesmen need employers’ liability insurance?

If you’re a tradesman running your own business, you might assume employers’ liability insurance only applies to corporate companies. But…

Contractors News 19 Jun 2026

The tax, pension and savings changes UK contractors need to keep on top of

The 2026/27 tax year might not be bringing one dramatic overhaul, but it marks the beginning of a multi-year shift…

Photo of dug out earth with construction worker on mini excavator, representing article on plant and machinery insurance
Trades Trades Life 01 Jun 2026

What is plant and machinery insurance?

From diggers and dumpers to cement mixers and compressors, plant and machinery are the backbone of many trades. Whether you’re…

Close-up of dates on a green calendar, representing article discussing claims made vs claims occurring in business insurance
Contractor Guides Contractors 26 May 2026

Simplifying insurance: what is claims made vs claims occurring

When you’re choosing insurance, you’ll often come across two terms: claims made and claims occurring. They both refer to the…

Tradesmen tools laid out on table, representing article on tool theft stories and keeping tools safe
Trades Trades Life 20 May 2026

Tool theft stories: tradespeople going beyond locks to keep tools safe

As tool theft continues to dominate headlines and social feeds, many tradespeople are no longer relying on standard security –…

Goodie bag from Powered Now Advice on Tap event, representing article on tradespeoples' concerns about tool insurance claims
Trades Trades Life 15 May 2026

Powered Now ‘Advice on Tap’: trade talk and tool theft troubles

Powered Now’s landmark event brings together tradespeople of all backgrounds. But conversations highlight the ongoing issue of tool theft, the…

Photo of builders discussing construction plans, representing article on what professional indemnity means for tradespeople
Trades Trades Life 28 Apr 2026

What is professional indemnity for tradespeople?

Many tradesmen assume professional indemnity is only for people with a desk job. But in reality, if your work involves…

Image of two builders carrying construction materials, representing article on do subcontrctors need their own insurance
Trades Trades Life 15 Apr 2026

Do subcontractors need their own insurance?

Knowing whether subcontractors need their own insurance can be confusing. Whether working in construction, roofing, plumbing, electrical work or specialist…

Image of construction hard hats representing a guide to what insurance a tradesman needs
Trades Trades Life 31 Mar 2026

What insurance does a tradesman need?

Insurance sounds like a good idea, but how do you know what insurance you need as a tradesman? No two…

Photo of a presentation screen at an event held by Kingsbridge on the JSL legislation and what it means for recruitment agencies
Partner News Partners 30 Mar 2026

What JSL will mean for you: Five lessons from our expert panel

Earlier this month Kingsbridge brought together a panel of industry experts to discuss the implications of the government’s new JSL…

Builder working on a house extension roof, representing a guide to contract works insurance for tradespeople including what it covers
Trades Trades Life 17 Mar 2026

What is contract works insurance?

However big or small your construction project is, contract works insurance could be a lifesaver if something happens. When you’re…

Image of bricklaying representing article on who needs trades insurance and what it covers
Trades Trades Life 10 Mar 2026

Who needs trades insurance?

If you work in the trades, chances are you’ve already heard people chatting about tradesman insurance, but have been left…

Calendar with date circled, representing guide on what a retroactive date is in professional indemnity insurance
Contractor Guides Contractors 26 Feb 2026

Professional indemnity insurance: what’s a retroactive date

Whether you’ve just taken out a professional indemnity policy or you’re shopping for new business insurance, chances are you’ve come…

HMRC Making Tax Digital campaign asset, representing article disucssing the upcoming changes for sole traders April 2026
Contractor Guides Contractors 16 Feb 2026

A ‘Making Tax Digital’ wake-up call for sole traders

The way Britain pays tax is entering its biggest modernisation in a generation, with Making Tax Digital (MTD) for Income…

Photo of HMRC London offices representing article discussing the Employment Rights Act 2025 being law, what changes it brings and what businesses need to do now
Partner News Partners 22 Jan 2026

Employment Rights Act 2025 ‘brings world of work into 21st century’

Big changes to the world of work have been on the horizon for a while and the Royal Assent of…

HMRC Self Assessment tax return letter for 2025 tax year sent to UK taxpayer with UTR and NINO
Contractor Guides Contractors 16 Jan 2026

Online Self Assessment tax return deadline: what to know for 2026 (and beyond)

If you’re required to file a Self Assessment tax return for the 2024/25 tax year, the deadline to submit it…

Contractor Guides Contractors 01 Jan 2026

What is the difference between a sole trader and a limited company?

One of the big questions for any contractor when they first set up as self-employed is whether you should operate as a…

Image of sparks caused by power tools, representing article on what makes a trade high risk for insurance
Trades Trades Life 18 Dec 2025

Trades cover: who’s considered high risk for insurance

If you’re in the trades, you already know the job isn’t without its risks. But did you know those risks…