Calculate your income tax, National Insurance, and total tax liability for 2026/27.
| Income | Income tax | Class 4 NI | Total |
|---|---|---|---|
| £40,000 self-employed profit | £5,486.00 | £1,645.80 | £7,131.80 |
| £60,000 self-employed profit | £11,432.00 | £2,456.60 | £13,888.60 |
| £20,000 profit plus £3,000 savings interest | £1,886.00 | £445.80 | £2,331.80 |
| £30,000 profit plus £25,000 dividends | £7,302.25 | £1,045.80 | £8,348.05 |
In the savings example, the first £1,000 of interest is covered by the Personal Savings Allowance, so only £2,000 is taxed. In the dividend example, £500 is covered by the dividend allowance and the rest is split between the 10.75% and 35.75% rates, because the dividends push total income past £50,270.
A first-year bill can be a shock: with a £7,131.80 bill you'd also owe a first payment on account of £3,565.90 on the same 31 January, so budget for roughly one and a half times the bill.
Income is taxed in the order HMRC uses: earnings and rental profit first, then savings interest, then dividends. Savings get the £5,000 starting rate where earnings are low and the Personal Savings Allowance (£1,000 for basic rate taxpayers, £500 for higher rate, none for additional rate). Pension contributions and Gift Aid extend your tax bands and reduce the income used for the £100,000 allowance taper.
It uses rest-of-UK income tax rates, so Scottish taxpayers should expect a different figure on earnings. If you're employed as well, some of the income tax shown will already have been paid through PAYE. Enter profit after allowable expenses, not turnover.
For the 2026/27 tax year, register by 5 October 2027 if you are new to Self Assessment, file a paper return by 31 October 2027, and file online and pay what you owe by 31 January 2028.
Usually yes if you were self-employed and earned more than £1,000 from it, received more than £1,000 in property income, had untaxed income such as tips or foreign income, or had dividends over £10,000. HMRC's online checker on GOV.UK will confirm it for your situation.
If your Self Assessment bill is more than £1,000, HMRC normally asks for two advance payments towards next year's bill, each half of this year's income tax and Class 4 National Insurance. They are due on 31 January and 31 July. You don't make them if more than 80% of your tax was already collected at source, for example through PAYE.
Not compulsorily. Since April 2024 self-employed people with profits above the Small Profits Threshold get National Insurance credits without paying Class 2. Those with lower profits can choose to pay voluntary Class 2 to protect their State Pension record.
There is an automatic £100 penalty if your return is up to 3 months late, even if you owe no tax. Further penalties and interest are added the longer it stays late.
Sources: GOV.UK: Self Assessment tax returns, payments on account and self-employed National Insurance rates. General information, not financial advice.