Estimate the income tax and National Insurance on your self-employed profit for 2026/27, plus the amount to set aside each month. Choose actual expenses or the trading allowance.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the Self-employed tax and National Insurance calculator works
The tool starts with your taxable profit: turnover minus either your actual expenses or the £1,000 trading allowance (you cannot claim both). It then works out:
- Income tax on the profit, using the Personal Allowance (reduced above £100,000) and the 20%, 40% and 45% bands for England, Wales and Northern Ireland.
- Class 4 National Insurance: 6% on profit between £12,570 and £50,270, and 2% above.
- Class 2: not charged; it is treated as paid once profit reaches the small profits threshold. Below it, a voluntary payment is shown for information only.
- Student loan if you choose a plan, plus the postgraduate loan.
- Payments on account: half of the income tax and Class 4 bill, due on 31 January and 31 July, shown as information.
The tool assumes no other income, no pension contributions and no losses. Rates are for 2026/27; check GOV.UK.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Self-employed income (turnover) | 40000 |
| Deduct | Actual expenses |
| Business expenses | 8000 |
| Student loan | No student loan |
| Postgraduate loan | No |
Tax and NI on your profit: £5,052
| Taxable profit | £32,000 |
|---|---|
| Income tax | £3,886 |
| Class 4 National Insurance | £1,166 |
| Class 2 National Insurance | £0 (treated as paid) |
| Total to pay | £5,052 |
| Left after tax and NI per year | £26,948 |
Tips and common mistakes
Set money aside every month rather than at the deadline, using the monthly figure shown. Keep all business receipts, because expenses reduce profit and so reduce both tax and National Insurance. The trading allowance helps only when your genuine expenses are below it, and the tool shows what the alternative would give. Payments on account can surprise people in their first or second year, so plan for a larger bill then. Making Tax Digital rules apply to some people, so check GOV.UK for your situation.
Frequently asked questions
Do I pay Class 2 National Insurance?
Class 2 is no longer compulsory. It is treated as paid if your profit is at or above the small profits threshold, and below that you can choose to pay it voluntarily to protect your State Pension record. Check GOV.UK.
Should I use the trading allowance or my expenses?
Use whichever gives the lower profit. If your real expenses are below the trading allowance, the allowance is better; otherwise claim your expenses.
What are payments on account?
They are advance payments towards next year’s bill, each half of the previous year’s income tax and Class 4 bill. They are normally not needed when the bill is under £1,000.
Guides that help
- Self-employed tax explained: income tax, National Insurance and payments on account
- UK income tax explained: bands, allowance and how it's worked out
- National Insurance for employees: what you pay and why