Inside vs Outside IR35
For any contractor working through a limited company, two little words carry big financial weight: inside or outside. Your IR35 status decides whether HMRC taxes you as an employee or as a genuine business, and the difference can be thousands of pounds a year in take-home pay. At Form My Company, we help contractors set up their limited companies correctly, and in this guide we explain the difference between inside and outside IR35 clearly, so you understand where you stand.
Because IR35 status is complex and getting it wrong carries real financial risk, this guide covers the principles, and we strongly recommend a specialist IR35 assessment or contractor accountant for your specific contracts.
The Core Difference
At its heart, the distinction is about whether you’re genuinely running a business or effectively working as an employee through a limited company, also known as a personal service company (PSC).
- Outside IR35 means you’re operating as a genuine, independent business. You’re taxed as self-employed through your company, and IR35 doesn’t apply to that engagement.
- Inside IR35 means HMRC considers you an employee for tax purposes for that contract, even though you work through a company. You’re taxed much like an employee.
The same contractor can be outside IR35 on one contract and inside on another, because status is assessed per engagement, not per person.
What Outside IR35 Means for You
Being outside IR35 is the more tax-efficient position, and it’s what most limited company contractors aim for. When you’re outside IR35, you operate as a genuine business, paying Corporation Tax on your company’s profits and drawing income through a mix of salary and dividends. You manage your own taxes, can claim legitimate business expenses, and keep full control of your company finances.
This flexibility is the main financial reason contractors choose a limited company over an umbrella. It’s worth noting one recent change, though. While the outside-IR35 position remains more tax-efficient, dividend tax rose in April 2026, which slightly narrows (but does not remove) the take-home advantage compared with previous years.
What Inside IR35 Means for You
Being inside IR35 changes the picture considerably. When a contract is inside IR35, that income is treated as employment income for tax. PAYE-style deductions for Income Tax and National Insurance are applied at source, usually by the fee-payer (often an agency) or an umbrella company. Your take-home pay is lower, and you lose the flexibility of the salary-and-dividends approach for that contract.
Importantly, being inside IR35 for tax doesn’t give you employment rights like holiday pay or sick pay, which is a common frustration for contractors caught by blanket determinations.
The Three Tests That Decide Your Status
There’s no single deciding factor. HMRC looks at the overall picture of your working relationship, using three key tests:
- Control. How much control does the client have over how, when, and where you carry out the work? Greater client control points toward inside IR35, while genuine autonomy supports outside status.
- Substitution. Do you have a genuine, unfettered right to send a qualified substitute to do the work? A real right of substitution is one of the strongest indicators of outside-IR35, self-employed status.
- Mutuality of obligation (MOO). Is the client obliged to provide ongoing work, and are you obliged to accept it? An ongoing expectation of work suggests employment, whereas project-based work with a defined end supports outside status.
A vital point: your actual working practices matter as much as your written contract. HMRC prioritises how you really work day to day over the wording on paper, so a contract labelled “outside IR35” won’t protect you if you’re treated like an employee in practice.
Who Decides: You or Your Client?
Who determines your status depends on the size of your end client, and this recently changed:
For medium and large private sector clients, and all public sector bodies, the client assesses your status and must issue a Status Determination Statement (SDS) explaining whether you’re inside or outside IR35 and why.
For small private sector clients, and clients based wholly overseas, you are responsible for determining your own status under the original Chapter 8 rules, taking reasonable care to get it right.
From April 2026, the thresholds defining a small company increased, meaning more contractors working for smaller clients are now responsible for their own determinations. If a client that was medium-sized is now classed as small, any previous determination no longer applies to future work, and you must make a fresh assessment.
How to Tell Which One You Are
While a proper assessment needs a specialist, some general questions can indicate your likely position. You’re more likely to be outside IR35 if you can send a substitute, control how you deliver the work, take on financial risk, use your own equipment, work on defined projects rather than open-ended tasks, and are free to work for other clients. You’re more likely to be inside IR35 if the client controls your hours and how you work, you can’t send a substitute, you’re integrated into the team like an employee, and there’s an ongoing obligation to provide and accept work.
Because no single answer is decisive, and the stakes are high, it’s well worth having both your contract and your working practices professionally reviewed.
Why the Distinction Matters So Much
The inside vs outside question is the single biggest factor in whether a limited company is financially worthwhile for a given contract. Outside IR35, the tax efficiency of a limited company shines. Inside IR35, much of that benefit disappears, which is why some contractors keep a limited company for outside-IR35 work and use an umbrella for inside-IR35 contracts. Getting the status right also protects you from HMRC investigations, backdated tax, interest, and penalties, which can be substantial.
How Form My Company Helps
We handle the foundation, getting your contractor limited company set up quickly and correctly, with a professional UK registered office address, identity verification support, and banking introductions. The IR35 status assessment itself is best handled with a specialist accountant, and with your company properly formed and good advice in place, you can contract with confidence whether your work is inside or outside IR35. Get started with your formation today.
Frequently Asked Questions
What does inside IR35 mean?
Inside IR35 means HMRC treats you as an employee for tax purposes on that contract, even though you work through a limited company. PAYE-style deductions apply at source, reducing your take-home pay compared with outside IR35.
What does outside IR35 mean?
Outside IR35 means you’re operating as a genuine business. You pay Corporation Tax on profits and draw a tax-efficient mix of salary and dividends, managing your own taxes. It’s the more tax-efficient position for contractors.
What’s the main difference in take-home pay?
Outside IR35 generally gives higher take-home pay through salary and dividends, while inside IR35 is taxed like employment via PAYE, reducing earnings. Dividend tax rose in April 2026, slightly narrowing but not removing the outside advantage.
Can I be inside IR35 on one contract and outside on another?
Yes. IR35 status is assessed per engagement, not per person. The same contractor can be outside IR35 on one contract and inside on another, depending on the working relationship for each.
What are the three IR35 tests?
Control, substitution, and mutuality of obligation. No single test decides your status; HMRC weighs the overall picture, and your actual working practices carry as much weight as your written contract.
Who decides if I’m inside or outside IR35?
For medium and large private sector and public sector clients, the client decides and issues a Status Determination Statement. For small private sector or wholly overseas clients, you determine your own status.
How can I tell if I’m inside or outside IR35?
Look at control, substitution, financial risk, and whether work is project-based. Genuine independence points to outside IR35; being managed like an employee points to inside. A professional contract and working-practices review is the reliable way to confirm.
