UK self-employed net income calculator (sole trader)
Your net income as a UK sole trader is profit minus income tax on everything above the personal allowance and Class 4 National Insurance at 6% between the lower and upper profits limits, then 2% above.
Worked example: with Annual profit after expenses of 50,000, this model computes Net income / year 40,268.20. See the full breakdown.
⚠ Illustrative rates Updated for 2026 · sources checked 2026-08-22
How sole trader in United Kingdom is calculated
A sole trader is taxed on profit, not turnover, through exactly the same income-tax bands an employee faces — but National Insurance works differently. Class 4 replaces the employee Class 1 charge and is deliberately cheaper: 6% on profit between the lower and upper limits, then 2% on everything above, with no employer contribution behind it at all.
The 2% upper rate is the part worth understanding. Above the upper profits limit the marginal National Insurance cost collapses from 6% to 2% while income tax steps up from 20% to 40%, so the combined marginal rate moves less than either component suggests. It is why comparing a sole trader against an employee on headline rates alone gets the answer wrong in both directions.
The personal allowance taper is modelled because it dominates one band: between 100,000 GBP and 125,140 GBP of profit the allowance withdraws at 1 GBP for every 2 GBP earned, producing an effective 60% marginal rate that is higher than anything above it. That mechanism has its own explainer, linked from this page.
Worked example
| Annual profit after expenses (GBP) | 50000 |
|---|---|
| Personal allowance ✓ | 12570 |
| Taxable Income ✓ | 37430 |
| Income tax ✓ | 7486 |
| Class 4 National Insurance ✓ | 2245.8 |
| Net income / year ✓ | 40268.2 |
Every row is computed by the engine from the inputs above. Rows marked ✓ are additionally pinned by a published self-test vector.
Frequently asked questions
How much net income from 50,000 GBP profit in the UK?
The full 12,570 GBP allowance leaves 37,430 GBP taxable at 20% — 7,486 GBP — plus 2,245.80 GBP of Class 4 National Insurance, for about 40,268 GBP net.
What is Class 4 National Insurance?
The self-employed National Insurance charge on profit: 6% between the lower profits limit and the upper profits limit, then 2% on profit above it. Class 2 was effectively abolished for most sole traders, so Class 4 is usually the whole National Insurance bill.
Does this apply in Scotland?
Only partly. Class 4 National Insurance is UK-wide, but Scotland sets its own income-tax bands and rates, which differ from the ones modelled here. A Scottish sole trader will see a different income-tax figure.
Sources
- HMRC — Income Tax rates and Personal Allowances (2026/27) · checked 2026-08-22
- HMRC — Self-employed National Insurance rates: Class 4 at 6% and 2% (2026/27) · checked 2026-08-22
Estimate. Not tax advice. The rates in this calculator are illustrative: they reproduce the shape of the charge through 3 self-test cases, but they are not the official schedule, so the amount shown will not match your bill. Use the official source above for that.
Check the arithmetic yourself: how this calculator is verified — the formula behind every derived value, the 3 test cases the engine reproduces, and what the badge does and does not claim. Also available as machine-readable JSON.
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