Hundred SummersSelf-employed tax calculator: profits to take-home, properly
Income tax on your profits (rest-of-UK or Scottish bands) plus Class 4 National Insurance at 6% between £12,570 and £50,270 and 2% above: the same band functions the Hundred Summers app charges in its projections, with the Class 2 abolition and payments-on-account timing explained rather than skipped. Your figures never leave your browser.
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Worked example
Computed when this page was built by the same engine that runs the calculator above, so the figures below and the live tool can never disagree. Change any input above to see your own.
| Inputs | |
|---|---|
| Profits | £45,000 |
| Scottish taxpayer | No |
| Results | |
|---|---|
| Income tax | £6,486 |
| Class 4 National Insurance | £1,946 |
| Take-home | £36,568 |
| A month | £3,047 |
| NI advantage over an employee on the same pay | £648 |
The next question
Sole trader or limited company? →Sole trader vs limited company
Or answer it with everything else: the full Hundred Summers plan connects your pay, pensions, savings, property, tax and spending year by year, and stress-tests them across 500 simulated market histories.
Read the guide
- Sole trader or limited company: the tax, and everything the tax ignores →Why the company route now loses at modest profits on 2026/27 rates and wins again higher up, what a director actually pays on salary and dividends, the Employment Allowance trap for one-person companies, and the non-tax reasons that often decide it.
The self-employment tax stack
Profits, turnover minus allowable expenses, bear ordinary income tax, then Class 4 NI on top. The NI is the quiet advantage of self-employment: 6% against an employee's 8%, and no employer NI in the chain at all. The calculator shows the gap. What self-employment lacks is an employer pension: no auto-enrolment, no matched contributions; a SIPP contribution reduces the income-tax line here (though not Class 4), and full relief still applies.
The engine behind this page is the same one the Hundred Summers app uses to project a self-employed career year by year: profits growth, pension relief, the State Pension your credited years buy, and retirement funded from what you build. Related: the employee take-home calculator for comparing a salaried offer, and the carry-forward calculator for catch-up contributions in a good year.