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Self-Employed Tax Calculator (Sole Trader)

Updated for tax year 2026/27 Business & Self-Employed HMRC guidance for the self-employed

If you are self-employed, you pay Income Tax and Class 4 National Insurance on your taxable profits, not your turnover. Profits are what is left after deducting your allowable business expenses.

Enter your annual turnover and expenses to see your taxable profit, the tax you will owe through Self Assessment, and what you keep.

Your details

Everything you received from selling your goods or services
Costs you can deduct, e.g. equipment, mileage, software

Results

Estimated tax & NI due
£5,831.80
Tax year 2026/27
Profit after tax
£29,168.20
Taxable profit
£35,000.00
Income Tax
£4,486.00
Class 4 National Insurance
£1,345.80
Student loan repayment
£0.00
Class 2 National Insurance
Treated as paid
Profits above £7,105 — worth ££190 a year

Income Tax on your profit

Tax-free (Personal Allowance)£12,570.00
Basic rate (20%)£4,486.00
Higher rate (40%)£0.00
Additional rate (45%)£0.00
Total Income Tax£4,486.00

Class 4 National Insurance

At 6% on profits up to £50,270£1,345.80
At 2% on profits above £50,270£0.00
Total Class 4£1,345.80

Where your profit goes

How the calculation works

We believe numbers should be transparent. Here is the formula behind this calculator.

Profit = Turnover − expenses · Income Tax + Class 4 NI (6% then 2%) + student loan repayments

Worked example

Worked example: £40,000 turnover in 2026/27

Turnover: £40,000. Allowable expenses: £5,000.
Taxable profit: £40,000 − £5,000 = £35,000.
Income Tax: Personal Allowance £12,570 means £22,430 is taxable at 20% → £4,486.
Class 4 NI: 6% on profits between £12,570 and £50,270 → £1,345.80.
Total due: £4,486 + £1,345.80 = £5,831.80. You keep £29,168.20.

Important assumptions

  • Assumes all income is self-employed profit and all expenses are allowable.
  • Class 2 is treated as paid when profits exceed the Small Profits Threshold, so no Class 2 is payable.
  • Class 4 NI is 6% on profits between £12,570 and £50,270 and 2% above £50,270.
  • Student loan repayments are based on total income, so this is an estimate.
  • Income tax uses England, Wales and Northern Ireland rates. Scottish rates differ.

Frequently asked questions

Do I pay Class 2 National Insurance?

Not since 2024/25 if your profits are above the Small Profits Threshold — your Class 2 contributions are treated as paid, which keeps your National Insurance record up to date. Below the threshold you can pay voluntarily.

What is the difference between turnover and profit?

Turnover is everything you receive for your goods or services. Profit is what is left after deducting your allowable business expenses — and it is your profit, not your turnover, that you pay Income Tax and Class 4 NI on.

When do I pay my self-assessment tax?

Your 2026/27 tax bill is usually due by 31 January 2028. Payments on account of roughly half of the bill are also due in January and July, so plan your cash flow early.

Related calculators

Income Tax Calculator

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Dividend Tax Calculator

Work out the tax on your dividends — the £500 allowance and the 8.75%, 33.75% and 39.35% rates.

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National Insurance Calculator

Work out your Class 1 employee National Insurance contributions and what you keep after NI.

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Student Loan Calculator

See how much of your income goes to student loan repayments, based on your plan and earnings.

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Related guides

New to the topic? Browse the guides section for plain-English explainers on business & self-employed, including worked examples and tips.

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These calculations are estimates for guidance only and are not professional financial, tax or legal advice. UK rates and rules change, so always verify important figures with official GOV.UK / HMRC information or speak to a qualified professional. See our full disclaimer.