Tool
Sole trader tax calculator
Trading profit through the allowance or real expenses, Class 2/4 National Insurance, income tax and next year's payments on account.
Everything invoiced or received this tax year, before any expenses.
What you actually spent running it. The £1,000 trading allowance is used instead whenever it's bigger.
Using your real expenses
£35,000 gross − £4,000 claimed = £31,000 taxable profit
What you keep
£26,208
per year
Income tax
£3,686
Class 4 NI
£1,106
Next year's payments on account
This year's bill clears the £1,000 minimum, so HMRC will expect £2,396 in advance on 31 January and another £2,396 on 31 July - half of this year's total each time, on top of what's actually owed for this year on the January bill.
A projection, not a return: models the trading allowance, Class 4 NI and income tax on trading profit correctly, but doesn't account for capital allowances, losses carried from another year, or other income using up your bands first. Class 2 has not been compulsory since April 2024 for anyone above the small profits threshold.
An illustration from the figures above, not a forecast. Facts, not financial advice.
Uses 2026/27 HMRC rates and thresholds, checked against gov.uk.
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