Self-Employed Tax Calculator
Work out the Income Tax and Class 4 National Insurance a sole trader owes on their trading profit — plus whether voluntary Class 2 contributions apply.
Estimate only. 2026/27 estimate — verify with gov.uk/HMRC; not tax advice.
Enter your trading profit
Your Income Tax, Class 4 National Insurance and net profit appear here as you type.
How sole-trader tax and National Insurance work
Self-employed sole traders pay Income Tax on their profit using the same Personal Allowance and bands as employees — 20% basic rate, 40% higher rate, 45% additional rate in England, Wales and Northern Ireland, or the Scottish bands in Scotland. On top of Income Tax, Class 4 National Insurance is charged at 6% on profits between £12,570 and £50,270, and 2% above that. Class 2 National Insurance became voluntary from April 2024: profits at or above the £6,725 Small Profits Threshold earn National Insurance credits automatically, while those below it can choose to pay a flat weekly rate to keep building entitlement to the State Pension and other contributory benefits.