About the UK Self-Employed Tax Calculator
This self-employed tax calculator estimates the Self Assessment bill a UK sole trader faces for the 2026/27 tax year (6 April 2026 to 5 April 2027). Enter your turnover and allowable expenses — or use the £1,000 trading allowance instead — and it works out your taxable profit, the income tax on that profit, Class 4 National Insurance and what you keep. If you also have a job, add your salary and the calculator shows only the extra tax caused by your self-employed profit, because PAYE already collects the tax on your wages.
It is designed for freelancers, side hustlers and full-time sole traders who want to know how much to set aside each month, and for anyone surprised by payments on account. When your Self Assessment bill is £1,000 or more and less than 80% of your total tax was collected at source, HMRC asks for two advance payments towards next year, so the first January payment can be up to 150% of the year’s bill. The calculator shows the 31 January 2028 and 31 July 2028 amounts.
Figures use the £12,570 personal allowance (tapered above £100,000), the 20/40/45% bands for England, Wales and Northern Ireland or Scotland’s six bands, and Class 4 NI at 6% on profits between £12,570 and £50,270 and 2% above. Class 2 NI is no longer compulsory; you can choose to pay £3.65 a week voluntarily to protect your State Pension when profits are below £7,105. Student loan repayments and other income types are not included.
With the default inputs, the tax and ni on your self-employed profit is £7,131.80. Change any value above to recalculate instantly.
How to use the uk self-employed tax calculator
- 1Enter your turnover for the tax year.
- 2Enter allowable expenses, or tick the £1,000 trading allowance if your costs are small.
- 3Add any employment income taxed through PAYE and choose Scotland if you live there.
- 4Read the tax and NI due on your profit and how much to set aside each month.
- 5Check the January and July figures to budget for payments on account.
Formula and method
Taxable profit is turnover minus allowable expenses; if you claim the £1,000 trading allowance you deduct that instead and cannot claim any other expenses. Income tax is worked out on your total income — any PAYE salary plus profit — using the £12,570 personal allowance (reduced by £1 for every £2 above £100,000) and the 20%, 40% and 45% bands (or Scotland’s 19%–48% bands). The salary’s own tax is subtracted because PAYE already collected it, leaving the extra tax caused by the business.
Class 4 National Insurance is charged on profits only, at 6% between £12,570 and £50,270 and 2% above. Payments on account are each half of the Self Assessment liability (income tax plus Class 4) and are required when that liability is at least £1,000 and less than 80% of your total tax was deducted at source. Voluntary Class 2 is £3.65 a week (£189.80 a year).
- Profit
- Turnover minus expenses or the trading allowance
- Class 4
- Self-employed National Insurance on profits
- POA
- Payment on account: 50% of this year’s bill, paid 31 January and 31 July
Worked examples
Sole trader with £40,000 profit
Profit is £45,000 − £5,000 = £40,000. Income tax is 20% of £27,430 = £5,486 and Class 4 is 6% of £27,430 = £1,645.80, a total of £7,131.80. As the bill exceeds £1,000, two payments on account of £3,565.90 follow, so January 2028 needs £10,697.70.
£70,000 profit in Scotland
Taxable income after the £12,570 allowance is £57,430. Scotland’s starter, basic and intermediate bands take £753.73 + £2,597.80 + £2,968.56, and 42% on the remaining £26,338 adds £11,061.96, so income tax is £17,382.05. Class 4 is £2,262 + £394.60 = £2,656.60, a total of £20,038.65.
Side hustle on top of a £30,000 job
The £1,000 trading allowance leaves £5,500 profit. Your salary already uses the personal allowance, so the profit is taxed at 20%: £1,100. Profit is under £12,570, so no Class 4 is due. The bill is over £1,000 and PAYE covered less than 80% of your total tax, so payments on account of £550 apply.
Frequently asked questions
How much tax does a self-employed person pay in the UK?+
Income tax at 20%, 40% or 45% on profit above the £12,570 personal allowance (Scotland has six bands from 19% to 48%), plus Class 4 National Insurance at 6% on profits between £12,570 and £50,270 and 2% above.
Do I still have to pay Class 2 National Insurance?+
No. Since 6 April 2024 self-employed people with profits of £7,105 or more get Class 2 credits automatically without paying. Below that you can pay £3.65 a week voluntarily (2026/27) to keep building State Pension entitlement.
What are payments on account?+
Advance payments towards next year’s bill, each equal to half of this year’s income tax and Class 4 NI. They are due on 31 January and 31 July unless your bill was under £1,000 or more than 80% of your tax was taken at source.
Should I use the £1,000 trading allowance?+
Use it if your actual allowable expenses are less than £1,000. If your gross trading income is £1,000 or less you do not even need to register. You cannot claim the allowance and deduct expenses at the same time.
When is the 2026/27 Self Assessment deadline?+
The online return and the balancing payment for 2026/27 are due by 31 January 2028, along with the first payment on account for 2027/28. Paper returns are due by 31 October 2027.
How much should I put aside for tax as a sole trader?+
Many basic-rate sole traders set aside 20–30% of profit. The calculator gives an exact monthly figure; remember the first year can need more cash because of payments on account.
Tax results are estimates based on published rules and simplified assumptions. They are not tax advice — check official guidance or a tax professional for your situation.