How is Class 4 National Insurance Calculated? (2026/27)
Class 4 National Insurance is a percentage of your self-employed profit: 6% between £12,570 and £50,270, then 2% above. Here is exactly how the calculation works, with worked examples.
The Class 4 thresholds and rates (2026/27)
| Profit band | Class 4 rate |
|---|---|
| Up to £12,570 (Lower Profits Limit) | 0% |
| £12,570 – £50,270 (Upper Profits Limit) | 6% |
| Over £50,270 | 2% |
Class 4 is based on your annual taxable profit (income minus allowable expenses) – the same figure you put on your Self Assessment return. It is separate from Class 2 and from Income Tax.
The formula in plain English
If your profit is below £12,570, you pay no Class 4 at all. Above that, only the profit above the threshold is taxed:
profit ≤ £12,570 → Class 4 = £0
£12,570 < profit ≤ £50,270 → Class 4 = 6% × (profit − £12,570)
profit > £50,270 → Class 4 = 6% × £37,700 + 2% × (profit − £50,270)
= £2,262 + 2% × (profit − £50,270)
Worked examples
| Profit | Calculation | Class 4 due |
|---|---|---|
| £20,000 | 6% × (£20,000 − £12,570) = 6% × £7,430 | £445.80 |
| £30,000 | 6% × (£30,000 − £12,570) = 6% × £17,430 | £1,045.80 |
| £50,000 | 6% × £37,430 | £2,245.80 |
| £60,000 | £2,262 + 2% × (£60,000 − £50,270) = £2,262 + £194.60 | £2,456.60 |
Once your profit passes £50,270, only the slice above it is charged at 2% – the first £37,700 of taxable profit is always at 6%.
Work out your Class 4 in seconds
Enter your profit and get Class 2 and Class 4 together, for 2026/27 or 2025/26.
Calculate your NI →When you do not pay Class 4
- Profit below £12,570 – no Class 4 is due.
- Over State Pension age at the start of the tax year.
- Limited company directors – you pay employee Class 1 NI on your salary instead, not Class 2/4.
FAQs
How is Class 4 National Insurance calculated?
6% of your profit between £12,570 and £50,270, plus 2% on anything above £50,270 (2026/27). Below £12,570 you pay nothing.
Do I pay Class 4 above £50,270?
Yes – 6% on the band up to £50,270 (£2,262 at the top) plus 2% on everything above.
When do I pay Class 4 National Insurance?
With Income Tax and Class 2 through Self Assessment, normally by 31 January after the tax year ends.
Do I pay Class 4 after State Pension age?
No – if you are over State Pension age at the start of the tax year, you do not pay Class 4.