Estimate UK self-employed Income Tax and Class 4 National Insurance from trading profit, with Self Assessment caveats.
Use this self-employed tax calculator to estimate Income Tax, Class 4 National Insurance and after-tax trading profit for the 2026/27 tax year. It is a planning estimate only and does not decide Self Assessment filing duties, expenses, VAT or accounting treatment.
These helpers are planning estimates only and cannot decide tax filing duties, accounting treatment, company law, dividend legality or the best salary/dividend mix.
| Personal Allowance used | £12,570 |
|---|---|
| Taxable profit | £47,430 |
| Class 2 status | treated as paid |
| Total tax and NI estimate | £13,889 |
Use this self-employed tax calculator to estimate Income Tax, Class 4 National Insurance and after-tax trading profit for the 2026/27 tax year. It is a planning estimate only and does not decide Self Assessment filing duties, expenses, VAT or accounting treatment.
| Tax/source year | 2026/27 |
|---|---|
| Region | England/Wales/Northern Ireland |
| Tax code basis | 1257L where the page uses PAYE defaults |
| Pension basis | No pension deduction unless this example says otherwise |
| Student loan basis | No student loan unless selected in this example |
| What is not decided here | PayBreakdown does not decide payroll correctness, lender approval, benefit entitlement or employer compliance, and does not give regulated financial, mortgage, debt, tax, payroll or legal advice. |
|---|
The figures on this page use the values below. Open the calculator if your example salary differs.
The calculator models trading profit after allowable expenses, then estimates tapered Personal Allowance, Income Tax and Class 4 National Insurance from the shared source data.
Use the after-tax profit estimate for budget planning, then check official Self Assessment guidance or an accountant before making filing or business decisions.
Use this self-employed tax calculator to estimate Income Tax, Class 4 National Insurance and after-tax trading profit for the 2026/27 tax year. It is a planning estimate only and does not decide Self Assessment filing duties, expenses, VAT or accounting treatment. Salary estimates can change when the tax year, UK region, tax code, pension method, student loan plan, pay frequency, bonus, overtime or salary-sacrifice assumptions change.
The useful figure for budgeting is usually take-home pay after Income Tax, National Insurance, pension deductions and student loan deductions. Gross pay helps compare jobs, while net pay is usually the better starting point for bills, savings and borrowing checks.
Real payslips can differ because payroll works by pay period and can include tax-code changes, pension method differences, student-loan starts or stops, taxable benefits, salary sacrifice, bonuses, overtime, arrears, refunds, or rounding. Match the calculator settings to the payslip before treating a difference as meaningful.
Two jobs with the same headline salary can feel different once pension contribution rate, employer pension method, student-loan plan, bonus pattern, overtime, tax code, region, salary sacrifice and pay frequency are considered. Compare the monthly net figure with commuting costs, bills and savings goals before deciding whether a higher gross salary improves the household plan.
Start by matching the pay basis: annual salary, hourly rate, weekly hours, pay frequency and whether the figure is full-year or part-year. Then match the deductions that usually move the result the most: pension method, pension rate, student-loan plan, postgraduate loan, tax code, Scottish or Welsh tax treatment, bonus, overtime, taxable benefits and salary sacrifice. If the page is a comparison page, keep both sides on the same tax year and pension method before reading the difference. If it is a required-salary or pro-rata page, treat the answer as a target estimate and rerun it with a cautious lower-income or higher-deduction scenario before using it for bills, rent, borrowing or savings.
Use the visible result as a starting point, then change the assumptions that apply to your situation. For salary pages, that usually means tax year, region, tax code, pension method, student loan plan, bonus, overtime and salary-sacrifice settings. For borrowing, debt or budget pages, it means the real payment amount, term, interest rate, balance, bill timing, savings target and any expected income change. Keep the result separate from advice or approval decisions: PayBreakdown helps you model the numbers, while official sources, employer records, provider documents and professional support are still the right place for final checks. If a change is close to a threshold, rerun the calculation with a cautious higher-cost or lower-income scenario before relying on the result.
It estimates Income Tax, Class 4 National Insurance, taxable profit and after-tax trading profit from a self-employed profit input for the selected tax year.
No. It does not model payments on account, losses, VAT, CIS, capital allowances, basis-period edge cases, Making Tax Digital or every expense and allowance.
No. It is a planning estimate only. Self Assessment registration, filing duties and deadlines should be checked with GOV.UK or a professional adviser.
No. Sole-trader searches use this self-employed tax calculator because the useful public task is the same.
Last updated 2026-08-19. Estimates are for planning and should be checked against official records where the decision matters.