UK self-employed tax calculator 2026/27
Estimate sole-trader Income Tax, Class 4 National Insurance, take-home profit and payment dates.
How the self-employed tax estimate works
The sole-trader calculator compares actual allowable expenses with the £1,000 trading allowance, adds taxable profit above other income and estimates Income Tax, Class 4 National Insurance and student-loan amounts.
Rules checked
Read the checking method
What the result includes
- Trading allowance or actual-expense routes
- Incremental Income Tax and Class 4 NI
- Payments-on-account screening and likely filing dates
What to have ready
- Gross turnover for 6 April 2026 to 5 April 2027
- Allowable expense receipts and any other taxable income
- Relief-at-source pension payments and student-loan details
Questions about self-employed tax
Does turnover below £1,000 always mean no action?
The trading allowance often removes a reporting requirement for that income alone, but exceptions apply and the allowance is shared across relevant trades. Keep records and check if another rule requires a return.
Why can the first January payment exceed the bill?
Where payments on account apply, HMRC normally asks for the balancing amount plus half of the next year’s expected Income Tax and Class 4 NI, with a second instalment in July.
Built for sole-trader profit
Uses 2026/27 Income Tax bands, the Personal Allowance taper, the £1,000 trading allowance, Class 4 National Insurance and current student-loan thresholds. The trading allowance is shared across relevant trades. It does not model VAT, losses, capital allowances or limited-company tax.