About This Calculator

IR35 Calc is a free, independent tool built to help UK contractors quickly understand the financial difference between working inside and outside IR35. We built it because existing tools were either outdated, confusing, or buried behind lead-capture forms.

The calculator uses UK 2026/27 tax year rates — employer NI 15%, secondary threshold £5,000, confirmed unchanged at GOV.UK. It assumes an optimal Ltd company structure (salary set to the personal allowance, remaining profits taken as dividends). Updated whenever HMRC changes relevant thresholds or rates.

Accuracy & Limitations

While we make every effort to keep the calculations accurate and up to date, this tool provides estimates only. It does not account for:

• Marginal cases — though personal allowance tapering above £100,000 IS included
• Scottish income tax rates (which differ from England, Wales and Northern Ireland)
• Marriage allowance or other personal tax adjustments
• Student loan repayments
• Benefits-in-kind or other non-cash income
• Previous tax year carry-forwards

Always consult a qualified accountant or tax adviser before making decisions based on these figures.

Not Financial Advice

This calculator does not constitute financial, tax or legal advice. IR35 status is a legal and factual determination based on your specific working arrangement — it cannot be decided by a calculator alone. We strongly recommend seeking professional advice from an IR35 specialist.

For official HMRC guidance, visit the HMRC IR35 guidance page.

Contact

Found a bug or have a suggestion? We welcome feedback. Please note we cannot provide individual tax advice.