UK Self-Employed Tax Calculator
Estimate Income Tax and Class 4 National Insurance on net sole-trader profit, with regional tax bands and the supported Class 2 treatment explained.
Rule year: 2026/27 · GBP · Sources checked
Estimated profit after Income Tax and Class 4 NI
Single ordinary sole-trader profit, no employment income, partnership allocation, losses, pensions, Gift Aid, student loans, payments on account or credits. Below-State-Pension-age Class 4 scope. No compulsory Class 2 charge is included; voluntary lower-profit payments and entitlement effects are not assessed.
Income Tax by band
Only non-savings, non-dividend income is included. Taxable income is measured after the allowance shown above; Scottish bands apply only when Scotland is selected.
| Band | Taxable slice | Rate | Tax |
|---|---|---|---|
| £0 to £37,700 | £37,430.00 | 20% | £7,486.00 |
| £37,700 to £125,140 | £0.00 | 40% | £0.00 |
| £125,140 to above | £0.00 | 45% | £0.00 |
For informational purposes only. This estimate is not financial advice, a tax return, a payroll calculation or a lender decision. See the supported circumstances and exclusions below.
How this calculator works
Start with net taxable profit after business costs and adjustments you have already established, not business turnover. The model applies the supported Personal Allowance and regional non-savings Income Tax bands, then adds Class 4 NI. Ordinary qualifying profits can receive treated-as-paid Class 2 coverage without a compulsory Class 2 amount. Lower-profit voluntary contributions are excluded. The result is profit after these two tax components, not necessarily cash available after all business commitments.
Formula and rules
Modelled profit after tax = net taxable profit − regional Income Tax − Class 4 NI. Class 4 uses 6% between £12,570 and £50,270, then 2% above that upper threshold.
Assumptions and limitations
Single ordinary sole-trader profit, no employment income, partnership allocation, losses, pensions, Gift Aid, student loans, payments on account or credits. Below-State-Pension-age Class 4 scope. No compulsory Class 2 charge is included; voluntary lower-profit payments and entitlement effects are not assessed.
Worked example
On £50,000 England profit with the standard allowance and no adjustments, Income Tax is £7,486 and Class 4 NI is £2,245.80. The model leaves £40,268.20 after those tax components, with no compulsory Class 2 charge included.
- Estimated profit after Income Tax and Class 4 NI
- £40,268.20
- Income Tax
- £7,486.00
- Class 4 National Insurance
- £2,245.80
- Monthly profit-after-tax equivalent
- £3,355.68
Official sources and review
Reviewed against the sources below on 2026-10-06. Rates are held in versioned rule modules. Versioned rules, official source review and year-specific calculation tests.
- GOV.UK: Income Tax rates and Personal Allowances ↗
2026/27 allowance £12,570, taper above £100,000, and income bands.
- HMRC: Rates and thresholds 2026 to 2027 ↗
Regional PAYE bands, Category A NI, student-loan plans and current minimum wage.
- GOV.UK: National Insurance rates ↗
Category A employee rates and Class 4 self-employed rates; no compulsory Class 2 charge in this model.
Common questions
Should I enter turnover or profit?
Enter net taxable sole-trader profit after the business adjustments you have established. The tool does not decide which expenses are deductible.
Are payments on account included?
No. Payment dates and payments on account affect cash timing rather than the simplified current-year tax total shown here.
What if I also have employment income?
Mixed employment, NI coordination and combined income require extra modelling. This tool is deliberately limited to the entered sole-trader-only scenario.