IR35 Calculator UK 2026: Inside vs Outside Take-Home Pay
IR35 calculator searches usually come from one stressful question: how much will I actually take home from this contract? If you are a UK contractor weighing up an inside-IR35 role against an outside-IR35 one, the difference can run into thousands of pounds a year, and the rules behind it are genuinely confusing. Day rates, umbrella margins, employer National Insurance, and tax bands all interact, so a headline rate tells you very little on its own. This guide explains how an IR35 calculator works, walks through real worked examples for 2026/27, and shows you exactly which figures to plug in.
An IR35 calculator estimates your contractor take-home pay by applying income tax, National Insurance, and, for inside-IR35 roles, umbrella deductions to your day rate. Outside IR35, a £500-a-day contractor typically keeps around £70,000 a year; inside IR35 via an umbrella, the same rate nets roughly £57,000 to £60,000.
- An IR35 calculator converts your day rate into realistic annual take-home pay.
- Inside IR35 usually means PAYE via an umbrella, with lower take-home than outside.
- Inside-IR35 contractors typically keep 60% to 70% of gross earnings.
- Employer NI of 15% above £5,000 and an umbrella margin reduce inside-IR35 pay.
- A common fix is raising your inside-IR35 day rate by 15% to 20%.
- The client usually decides your status, unless they are a small company.
What is an IR35 calculator?
An IR35 calculator is a tool that turns your contract day rate into an estimate of your real annual take-home pay, after all the tax and deductions that apply to your working arrangement.
IR35, also called the off-payroll working rules, is the UK tax legislation that decides whether a contractor should be taxed like an employee. If your role is judged “inside IR35”, you are taxed broadly as an employee, usually through an umbrella company on PAYE. If it is “outside IR35”, you can operate through your own limited company with more tax efficiency.
Because the two routes are taxed so differently, the same day rate produces very different take-home pay. A good calculator accounts for income tax, National Insurance, umbrella margins, and employer costs. To understand the deductions a calculator applies, it helps to first read our guide to UK tax codes explained for 2026.
Inside versus outside IR35
The single biggest factor in your take-home pay is whether your contract sits inside or outside IR35. Here is what each means in practice.
Outside IR35
You provide services as a genuine business, typically through your own limited company. You pay corporation tax and can draw income as a mix of salary and dividends, which is more tax-efficient. You also carry more responsibility and risk.
Inside IR35
Your role is treated like employment for tax. Most inside-IR35 contractors work through an umbrella company, which acts as your employer, deducts PAYE tax, both sets of National Insurance, and a margin, then pays you the rest. Take-home is lower, but admin is simpler.
| Feature | Outside IR35 | Inside IR35 |
|---|---|---|
| Structure | Limited company | Umbrella / PAYE |
| Tax efficiency | Higher | Lower |
| Take-home (of gross) | Roughly 70%+ | Roughly 60% to 70% |
| Admin burden | Higher | Lower |
Worked take-home examples for 2026/27
Numbers make this clearer than definitions. These worked examples use the 2026/27 tax thresholds: a £12,570 personal allowance, 20% basic rate to £50,270, and 40% higher rate above that.
Example 1: £250 a day, inside IR35
At £250 a day for 220 working days, gross turnover is £55,000. After the umbrella margin, employer National Insurance, PAYE tax, and employee National Insurance, take-home lands around £37,000 a year, or roughly 67% of gross.
Example 2: £500 a day, outside IR35
At £500 a day for 220 days, gross is £110,000. Operating outside IR35 through a limited company, typical take-home is around £70,000 to £75,000 after corporation tax and personal tax on salary and dividends.
Example 3: £500 a day, inside IR35
The same £500 day rate inside IR35 via an umbrella nets roughly £57,000 to £60,000. That is a difference of around £4,000 to £5,000 a year compared with the outside-IR35 figure on the lower estimate, and more on higher rates.
| Day rate | Status | Approx. annual take-home |
|---|---|---|
| £250 (220 days) | Inside IR35 | ~£37,000 |
| £500 (220 days) | Inside IR35 | ~£57,000 – £60,000 |
| £500 (220 days) | Outside IR35 | ~£70,000 – £75,000 |
These are estimates, not promises. Your real figure depends on pension contributions, expenses, your umbrella’s margin, and how you draw income. For a sense of how a comparable employed salary nets down, our breakdown of £50k after tax in the UK is a useful reference.
How to calculate your take-home pay
You can sanity-check any calculator by working through the steps yourself. Here is the inside-IR35 umbrella method.
- Find your gross. Multiply your day rate by the days you expect to work in a year (220 is a common assumption after holidays).
- Deduct the umbrella margin. Umbrellas typically charge £25 to £40 a week.
- Deduct employer National Insurance. This is 15% on earnings above the £5,000 secondary threshold, plus the 0.5% Apprenticeship Levy.
- Apply income tax. Use the personal allowance and bands: 20% basic, 40% higher, 45% additional.
- Apply employee National Insurance. 8% on earnings between £12,570 and £50,270, then 2% above.
The result is your estimated take-home. Checking this against your payslip each month ensures the umbrella has applied everything correctly. Our guide on how to read a UK payslip shows you what each line should contain. If you want to build your own quick model, Coffee & Study’s finance and accounting courses cover the spreadsheet skills to do it accurately.
Who decides your IR35 status?
Since the off-payroll rules were extended to the private sector, status decisions usually sit with the client, not the contractor.
In most cases the client, the organisation you work for, is responsible for determining your employment status. However, if you provide services to a small company outside the public sector, your own intermediary, normally your limited company, decides whether the rules apply.
A company counts as small if it meets at least two of three thresholds: turnover not more than £15 million, a balance sheet total not more than £7.5 million, and no more than 50 employees. HMRC’s Check Employment Status for Tax (CEST) tool can help assess status, though it cannot reach a conclusion in every case, so professional advice is often worthwhile. Understanding your contract terms also matters, and our guide to UK employment contracts explained covers the basics.
Adjusting your day rate for IR35
If a role moves inside IR35, your take-home drops unless your rate rises. Many contractors negotiate accordingly.
A common approach is to increase your inside-IR35 day rate by 15% to 20% to offset the extra employer National Insurance and reduced tax efficiency. For example, an outside-IR35 rate of £500 a day might need to become £575 to £600 a day inside IR35 to leave you in a similar net position.
When comparing a contract offer with a permanent salary, run both through a calculator before deciding. A higher day rate can still net less than a permanent role once benefits, pension, and holiday pay are included.
Common Mistakes to Avoid
Comparing day rate to salary directly
A £500 day rate is not equivalent to a £130,000 salary. After unpaid holidays, gaps between contracts, and tax, the real comparison is much closer. Always convert to annual take-home first.
Forgetting employer National Insurance inside IR35
Inside IR35 via an umbrella, employer National Insurance of 15% above the £5,000 threshold comes out of the assignment rate before your pay. Contractors who overlook this are often shocked by their first payslip.
Assuming all umbrella companies are the same
Umbrella margins and processes vary. Some also promote arrangements that are too good to be true. Stick to compliant umbrellas and treat any promise of unusually high take-home with caution.
Not negotiating the inside-IR35 rate
If a role is inside IR35, your take-home falls unless your rate rises. Many contractors accept the same rate they would have taken outside IR35 and lose thousands. Negotiate a 15% to 20% uplift where you can.
Frequently Asked Questions
How accurate is an IR35 calculator?
An IR35 calculator gives a close estimate, not an exact figure. It applies current tax bands, National Insurance, and umbrella deductions to your day rate, but your real take-home depends on pension contributions, expenses, your umbrella’s margin, and how you draw income. Use it to compare inside and outside roles and to sanity-check offers, then confirm details with your umbrella or accountant.
How much less do you take home inside IR35?
Inside IR35 you typically take home 60% to 70% of gross, compared with around 70% or more outside IR35. On a £500 day rate, that can mean roughly £57,000 to £60,000 inside versus £70,000 to £75,000 outside, a difference of several thousand pounds a year. The gap widens at higher day rates.
Who pays employer National Insurance inside IR35?
Inside IR35 via an umbrella company, employer National Insurance is deducted from the assignment rate the client pays the umbrella, before your taxable pay is calculated. In effect it reduces your take-home. It is charged at 15% on earnings above the £5,000 secondary threshold, alongside the 0.5% Apprenticeship Levy.
Who decides if a contract is inside or outside IR35?
For most private-sector contracts the client decides your IR35 status. The exception is when you work for a small company, defined as meeting at least two of: turnover up to £15 million, balance sheet up to £7.5 million, and up to 50 employees. In that case your own limited company makes the determination. HMRC’s CEST tool can help assess status.
Should I increase my day rate if a role is inside IR35?
Yes, if you can. Because inside-IR35 take-home is lower, many contractors raise their day rate by 15% to 20% to offset employer National Insurance and reduced tax efficiency. An outside rate of £500 a day might become £575 to £600 inside IR35 to keep your net pay broadly the same. Always negotiate before accepting.
Comparing contract and permanent roles? Browse current openings on our UK jobs board, or explore more pay and tax guidance in our Career Advice section to make the right call for your take-home pay.
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