Calculator · Self-employed

Self Assessment estimator

Estimate Income Tax and Class 4 National Insurance for 2026/27, then use the payment-on-account illustration to plan cash flow.

Tax year 2026/27

Calculator answer

Enter your figures to estimate the result for the 2026/27 tax year. The output is a planning estimate only and should be checked against HMRC guidance before filing or paying tax.

Self-employed profit

Other taxable income

Use professional advice for savings or property income.Tax already paid at source

PAYE or other tax deductions already made.

Indicative amount for 31 January

£8,748

Income Tax (all entered income): £4,486
Class 4 NI: £1,346
Total estimated liability: £5,832
Less tax already paid: −£0
Indicative balancing payment: £5,832
Indicative first payment on account: £2,916
Indicative second payment on account (31 July): £2,916

How this calculator works

This calculator applies the 2026/27 England, Wales and Northern Ireland income-tax bands, standard personal allowance and Class 4 National Insurance to a simplified total-income scenario. It does not model Scottish bands, savings or property-income rules, capital gains, pension relief, student loans, benefits, loss relief or every Self Assessment adjustment.

Payments on account are usually two 50% instalments toward the next tax year, but whether they apply also depends on source deductions and the previous year’s bill. The figure shown is a cash-flow illustration only; HMRC’s calculation is controlling.

Compulsory Class 2 National Insurance has been abolished. Voluntary contributions and National Insurance credits can depend on profits and circumstances; check HMRC guidance if protecting entitlement matters to you.