Inside IR35 Calculator UK 2026: Your Take-Home Pay
Inside IR35 calculator UK 2026 searches spike whenever a contractor receives a contract that has been assessed as “inside IR35”, because the first question is always the same: how much will I actually take home? If you have spent years as an outside-IR35 limited company contractor, an inside-IR35 assignment can feel like a pay cut, and working out the real figure is genuinely confusing. Employer National Insurance, the apprenticeship levy, umbrella margins, and your own income tax and National Insurance all come out before the money reaches you. This guide explains exactly how an inside IR35 calculation works for 2026/27, walks through a clear worked example, and shows you how to estimate your own take-home pay.
An inside IR35 calculator UK 2026 estimates your take-home pay by deducting employer-side costs (employer National Insurance at 15 per cent, the 0.5 per cent apprenticeship levy, and the umbrella margin) from your assignment rate to find your deemed salary, then applying your personal income tax and National Insurance. For a typical contractor, take-home is roughly 45 to 55 per cent of the gross assignment rate.
- Inside IR35 means you are taxed broadly like an employee, with income tax and National Insurance deducted at source.
- Employer’s NI (15 per cent above £5,000) and the 0.5 per cent apprenticeship levy come out of your assignment rate before your gross pay is set.
- Umbrella company margins are typically £15 to £35 per week and are separate from statutory deductions.
- Take-home pay is usually around 45 to 55 per cent of the gross assignment rate, depending on rate, pension, and tax code.
- Salary-sacrifice pension contributions are one of the few legitimate ways to improve your net position.
- Always compare the assignment rate, not a notional “salary”, when weighing up an inside-IR35 contract.
What Inside IR35 Means
IR35 is the UK’s set of off-payroll working rules. They exist to stop people who are effectively employees from paying less tax by working through their own limited company. If a contract is assessed as “inside IR35”, HMRC treats you, for tax purposes, much like an employee of the end client.
In practice, most inside-IR35 contractors are paid through an umbrella company. The umbrella becomes your employer, runs PAYE on your earnings, and deducts income tax and National Insurance before paying you. That is why an inside IR35 calculator is so useful: the deductions are layered, and the headline assignment rate is nowhere near your net pay.
How an Inside IR35 Calculation Works
The key concept to grasp is the difference between the assignment rate and your deemed salary. The assignment rate is the full amount the agency or client pays to the umbrella. Your deemed salary is what is left after employer-side costs are removed, and it is from this lower figure that your own tax and National Insurance are then calculated.
The deductions happen in two stages.
Stage one: employer-side costs come off the assignment rate. These reduce the assignment rate down to your gross (deemed) salary:
- Umbrella company margin (typically £15 to £35 per week).
- Employer’s National Insurance, charged at 15 per cent on earnings above the £5,000 secondary threshold for 2026/27.
- Apprenticeship levy at 0.5 per cent.
- Employer pension contribution, if you choose to make one.
Stage two: your personal deductions come off the deemed salary. Once your gross salary is set, the umbrella applies standard PAYE:
- Income tax (20 per cent, 40 per cent, or 45 per cent depending on your band).
- Employee’s National Insurance (8 per cent between £12,570 and £50,270, then 2 per cent above).
- Employee pension contribution and student loan repayments, where they apply.
What lands in your bank account is your deemed salary minus those personal deductions. This is the same PAYE system every UK employee uses, so understanding it is much easier once you can read a payslip; our guide on how to read a UK payslip explains every line you will see.
Worked Example: A £500-a-Day Contract
Let us run a realistic example for 2026/27. Assume a £500 per day assignment rate, 46 working weeks per year (allowing for holidays and gaps between contracts), and a standard tax code with no pension contribution.
| Step | Approximate amount |
|---|---|
| Assignment rate (£500 × 5 days × 46 weeks) | £115,000 |
| Less umbrella margin (approx £25/week) | –£1,150 |
| Less employer’s NI (15 per cent) and apprenticeship levy (0.5 per cent) | –£14,000 to £15,000 |
| Deemed gross salary | approx £99,000 |
| Less income tax and employee’s NI | –£33,000 to £36,000 |
| Estimated annual take-home | approx £63,000 to £66,000 |
These figures are illustrative and rounded, and your exact numbers will vary with your tax code, pension choices, and the umbrella’s margin. As a rule of thumb, the effective deduction rate for a typical inside-IR35 contractor lands somewhere between 45 and 55 per cent of the gross assignment rate. For a sense check on the personal-tax side of the calculation, our breakdown of £50,000 after tax in the UK shows how income tax and National Insurance stack up at a comparable salary.
2026/27 Tax and National Insurance Rates
An accurate inside IR35 calculation relies on the current thresholds. For 2026/27 the key figures are:
- Personal Allowance: £12,570
- Basic rate (20 per cent): £12,571 to £50,270
- Higher rate (40 per cent): £50,271 to £125,140
- Additional rate (45 per cent): over £125,140
- Employee’s NI: 8 per cent on £12,570 to £50,270, then 2 per cent above
- Employer’s NI: 15 per cent on earnings above the £5,000 secondary threshold
- Apprenticeship levy: 0.5 per cent
If your take-home looks lower than expected, your tax code is often the reason. An incorrect code can leave you overpaying for months. Our guide to UK tax codes explained shows how to check yours and fix it if it is wrong.
How to Improve Your Take-Home Pay
Inside-IR35 deductions are largely fixed, but a few legitimate levers remain:
- Use salary-sacrifice pension contributions. Routing money into a pension before tax saves income tax, employee NI, and employer NI, which makes it one of the most efficient options available.
- Check your tax code. Make sure HMRC has the right code so you are not overpaying tax through the year.
- Compare umbrella margins. Margins vary between providers, and over a year the difference can be several hundred pounds.
- Negotiate the assignment rate. Because employer costs now come out of the rate, it is reasonable to seek a higher inside-IR35 rate than you would have charged outside.
- Keep accurate records. Track expenses and pension contributions so you can reconcile your PAYE position at year end.
If you are weighing up contracting against a permanent finance or operations role, brushing up your numerical and modelling skills helps in either direction. Coffee & Study’s finance and accounting courses are a practical way to get more confident with the figures behind your own pay.
Common Mistakes to Avoid
Comparing the assignment rate to a permanent salary
An inside-IR35 assignment rate is not equivalent to a salary, because employer costs are deducted from it. Comparing a £115,000 assignment rate directly to a £115,000 salary will badly mislead you. Always compare net take-home figures.
Forgetting employer NI comes out of your rate
Many new inside-IR35 contractors are shocked to see employer’s National Insurance deducted from their pay. Under these arrangements that cost is effectively passed to you through the assignment rate, so factor it in before accepting a contract.
Choosing an umbrella on margin alone
A slightly lower margin is not worth it if the provider is unreliable or non-compliant. Check that any umbrella runs proper PAYE and avoid any scheme promising unusually high take-home pay, as these are often tax-avoidance arrangements that HMRC will challenge.
Ignoring pension tax relief
Skipping pension contributions because you want maximum monthly cash is a common error. Salary sacrifice is one of the only ways to genuinely cut your inside-IR35 deductions, and ignoring it leaves money on the table.
Frequently Asked Questions
How much do you take home inside IR35?
Most inside-IR35 contractors take home roughly 45 to 55 per cent of their gross assignment rate. The exact figure depends on your rate, tax code, pension contributions, and the umbrella’s margin. The reduction is larger than for an equivalent salary because employer’s National Insurance and the apprenticeship levy are deducted from the assignment rate before your own tax applies.
Why is my inside IR35 pay so low?
Inside-IR35 pay looks low because deductions happen in two layers. First, employer’s NI (15 per cent), the 0.5 per cent apprenticeship levy, and the umbrella margin reduce your assignment rate to a deemed salary. Then income tax and employee’s NI come off that salary. Together these can remove around half of the headline rate.
Is it worth working inside IR35?
It can be, particularly if the assignment rate is high enough to offset the extra deductions or the role offers other benefits. Many contractors negotiate a higher inside-IR35 rate to compensate. Whether it is worthwhile depends on your rate, your alternatives, and how much you value the simplicity of PAYE over running a limited company.
Do I pay employer National Insurance inside IR35?
Technically the umbrella company pays employer’s National Insurance, but the cost is funded from your assignment rate, so in practice it reduces what you take home. This is why an inside-IR35 assignment rate should be higher than the salary you would accept for an equivalent permanent role.
How accurate are online inside IR35 calculators?
Good calculators using current 2026/27 rates give a reliable estimate, but they are only as accurate as the inputs you provide. Your real take-home depends on your specific tax code, pension contributions, student loan status, and the umbrella’s exact margin, so treat any calculator result as a close guide rather than an exact figure.
Ready to find your next contract? Browse the latest contractor and permanent vacancies on our UK jobs board and use the figures above to negotiate a rate that genuinely works for you.
Discover more from UK Jobs Alert
Subscribe to get the latest posts sent to your email.
