Question 1

What is IR35?

Accepted Answer

IR35 is a UK tax legislation designed to assess whether a contractor is a genuine business or essentially working as an employee. It affects how you are taxed and whether you pay through PAYE. For more details, see our article on Understanding IR35.

Question 2

What does 'inside' and 'outside' IR35 mean?

Accepted Answer

Inside IR35 means you're treated like an employee for tax purposes; outside IR35 means you're considered self-employed and can pay yourself via salary and dividends. This impacts your choice of trading structure. See our guide on Understanding IR35 for more details.

Question 3

How does IR35 affect my take-home pay?

Accepted Answer

If you fall inside IR35, your income is taxed under PAYE, reducing your net earnings. You lose some benefits of operating through a limited company, like claiming expenses and dividends. Explore strategies for Maximising Your Take-Home Pay, understanding Business Expenses, and how to calculate your gross to net pay.

Question 4

Can I still claim expenses under IR35?

Accepted Answer

Generally no, unless you're using an umbrella company. Most regular business expenses aren't deductible inside IR35. For Outside IR35 expense details, see Navigating Business Expenses.

Question 5

How accurate is this IR35 calculator?

Accepted Answer

The calculator is based on 2025/2026 UK tax rules and is regularly updated, but it's for guidance only. It does not constitute professional tax advice. Please read our Disclaimer. For a guide on using the calculator, see How to Calculate Your Gross to Net Pay.

Question 6

Do I need to enter personal data?

Accepted Answer

No personal data is saved or stored. All calculations are done in-browser for privacy and speed. See our Privacy Policy for more.

Question 7

How does salary sacrifice affect my IR35 calculation?

Accepted Answer

Salary sacrifice can reduce taxable income, so the calculator adjusts for this when selected. It assumes the contributions are made before tax. Learn more about Pension Strategies for Contractors, including salary sacrifice.

Question 8

What’s the difference between Plan 1 and Plan 2 student loans?

Accepted Answer

Plan 1 applies to older UK student loans with a lower repayment threshold. Plan 2 is for newer loans with a higher threshold. The calculator uses the correct rate for each plan.

Question 9

Can HMRC review my IR35 status retroactively?

Accepted Answer

Yes, HMRC can open an inquiry and challenge past contracts. It’s important to maintain proper documentation and contract reviews. Understanding your obligations under IR35 is key, and you might consider IR35 insurance.

Question 10

Should I use the CEST tool or this calculator?

Accepted Answer

The CEST tool is HMRC’s official tool for determining IR35 status, but many find it inconclusive. This calculator helps estimate financial impact but doesn't determine status. You might also consider IR35 insurance for peace of mind.

Question 11

Is the calculator mobile-friendly?

Accepted Answer

Yes, it’s fully responsive and tested on modern mobile browsers.

Question 12

Do I need to install anything to use the calculator?

Accepted Answer

No installation is needed. It runs entirely in-browser and is free to use.

Question 13

Does IR35 apply to IT contractors?

Accepted Answer

Yes, IR35 applies to IT contractors, especially those working long-term for a single client. Always assess your status on a per-contract basis. Our guide on Understanding IR35 can help.

Question 14

What about locum doctors or nurses?

Accepted Answer

Yes, healthcare professionals can fall inside IR35 depending on their contract terms. It’s common in NHS settings under agency arrangements. Refer to Understanding IR35 for general principles.

Question 15

How can I improve my tax efficiency if I’m inside IR35?

Accepted Answer

Consider using an umbrella company (see Choosing Your Trading Structure), salary sacrifice for pensions (see Pension Strategies), or negotiating better rates to offset taxes.

Question 16

Are there common mistakes contractors make with IR35?

Accepted Answer

Yes—misclassifying status, lacking written contracts, or relying solely on job titles instead of actual working practices. Our article on Understanding IR35 covers key determination factors.

Contractor Pay Guide

General IR35 Questions

IR35 and Take-Home Pay

Using the Calculator

Tax-Specific Scenarios

Legal and Compliance

Mobile/Technical Usability

Questions by Job Type

Optimization Tips