UK Self-Employed Tax Calculator 2026/27
Estimate income tax and Class 2 & 4 National Insurance on self-employed trading profit using HMRC rates.
Last updated: June 2026
Self Assessment inputs
45.00 Thousand
5.00 Thousand
Trading profit
£40,000
Total tax & NI
£7,311
Net profit after tax
£32,689
Effective rate
18.3%
Income tax
£5,486
Class 2 NI
£179
Class 4 NI
£1,646
Income tax breakdown
- Basic rate (20%)£5,486
Data sources
Rates and thresholds on this page are based on official publications. Verify against the source for your specific circumstances.
- HMRC / GOV.UK — verified 2026-06-01 · Income tax bands and personal allowance for 2026/27
- GOV.UK — National Insurance for self-employed — verified 2026-06-01 · Class 2 and Class 4 NI rates and thresholds
- GOV.UK — Self Assessment tax returns — verified 2026-06-01 · How trading profits are reported and taxed
How Self-Employed Tax Works
Self-employed traders pay income tax on trading profit (turnover minus allowable business expenses) through Self Assessment. The personal allowance and income tax bands match employment, though Scotland has its own rates.
On top of income tax, most self-employed people pay Class 2 NI (a flat weekly amount if profits exceed £12,570) and Class 4 NI (6% on profits between £12,570 and £50,270, then 2% above that). Class 4 is charged on profits, not on income after your personal allowance.
For example, with £50,000 turnover and £8,000 expenses, trading profit is £42,000. You would pay income tax on profit after the personal allowance, plus Class 2 (£179.40 per year) and Class 4 NI on the profit band.
This calculator provides estimates only and does not cover VAT registration, payments on account, or all Self Assessment rules. Consult HMRC or a qualified accountant for your tax return.