The free self-employed tax calculator for UK sole traders

This calculator provides a plain-English estimate of 2026/27 Income Tax and Class 4 National Insurance. Enter your income and allowable expenses to see an estimated bill, an effective rate and a monthly amount to put aside. It is designed for sole traders in England, Wales and Northern Ireland. Scottish Income Tax bands are different and are not included.

The free self-employed tax calculator for UK sole traders

This calculator provides a plain-English estimate of 2026/27 Income Tax and Class 4 National Insurance. Enter your income and allowable expenses to see an estimated bill, an effective rate and a monthly amount to put aside. It is designed for sole traders in England, Wales and Northern Ireland. Scottish Income Tax bands are different and are not included.

Total tax to set aside

£6,092
about £508 a month, roughly 14% of everything you invoice
Taxable profit
£36,000
You keep
£29,908
Effective rate
16.9%
  • Turnover£45,000
  • Business expenses− £9,000
  • Taxable profit£36,000
  • Income Tax− £4,686
  • Class 4 National Insurance− £1,406
  • You keep£29,908
Set aside £508 a month. Based on these figures, putting roughly 14% of each payment into a separate tax pot would build towards the estimated bill.
Budget for payments on account. Your Income Tax and Class 4 NI come to £6,092. Payments on account may apply, but they are not normally required if more than 80% of the tax due was collected outside Self Assessment. If they apply, the first 31 January payment would be about£9,138, with another £3,046 due on 31 July.

How the calculator works

You are taxed on your profit, not your turnover. Profit is what you invoice after allowable business costs such as materials, tools, van running costs and insurance. The calculator takes your income and expenses, works out that taxable profit, and then applies the current Income Tax bands and Class 4 National Insurance rates on top.

Because tax is worked out on a sliding scale, the more you earn the higher the percentage that goes to HMRC. The calculator shows an estimated bill, your effective tax rate and a suggested amount to move into a separate savings pot from each payment.

What shapes your tax estimate

Once you know these, the rest is arithmetic.

1. Your taxable profit

Turnover minus allowable business costs. This is the figure used for the estimate, rather than the amount you invoiced.

2. Income Tax on the bands

The first £12,570 of profit is tax free. After that, the relevant slice is taxed at 20% up to £50,270, then 40% and then 45%.

3. Class 4 National Insurance

On top of Income Tax you pay 6% NI on profit between £12,570 and £50,270, then 2% above. Class 2 is no longer compulsory for most.

Self-employed tax rates for 2026/27

For a sole trader in England, Wales or Northern Ireland, the headline figures for the 2026/27 tax year are:

  • Personal Allowance (tax free): £12,570, tapered above £100,000.

  • Basic rate: 20% on profit up to £50,270.

  • Higher rate: 40% from £50,270 to £125,140.

  • Additional rate: 45% over £125,140.

  • Class 4 National Insurance: 6% between £12,570 and £50,270, then 2% above.

  • Class 2 National Insurance: no longer compulsory for most sole traders.

The Personal Allowance is gradually removed once your income passes £100,000, so very high earners lose part of it. For most trades, though, the bands above are all you need to estimate what you owe.

Frequently asked questions

How much tax will I pay as a self-employed sole trader?

It depends on your profit. In the example above, £36,000 of taxable profit produces an estimated combined Income Tax and Class 4 National Insurance bill of about £6,000 for 2026/27. Enter your own figures for an estimate.

How much should I set aside for tax?

For planning, there is no fixed percentage that suits every sole trader. Allow separately for payments on account, student loans and other income. The calculator gives you a starting figure based on your own numbers. Payments on account are not normally required if more than 80% of the tax due was collected outside Self Assessment.

Do I pay National Insurance when I am self-employed?

Yes. Self-employed sole traders pay Class 4 National Insurance on their profits. For 2026/27, the rate is 6% between £12,570 and £50,270, then 2% above that. The calculator includes it alongside the Income Tax estimate.

What are payments on account?

Payments on account are advance payments towards your next bill, usually due on 31 January and 31 July. They normally apply when less than 80% of your tax is collected outside Self Assessment and the amount due is at least £1,000. Your HMRC statement confirms whether they apply and how much to pay.

Is this self-employed tax calculator accurate?

It gives a rough estimate using the published 2026/27 Personal Allowance, Income Tax bands and Class 4 National Insurance rates for England, Wales and Northern Ireland. It is a guide to help you plan and set money aside, not a substitute for filing your Self Assessment return. Scotland sets its own Income Tax bands, so the figures here do not apply there.

Related tools and guides

Written by Chris, founder of TradePilot. Last reviewed 10 September 2026. Figures on this page use the 2026/27 tax year for England, Wales and Northern Ireland. This is general information, not tax advice.

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