Self-employed tax calculator

How self-employed tax is worked out

How much tax do I pay on £35,000 of self-employed profit?

In England, Wales or Northern Ireland the first £12,570 is covered by your personal allowance and the other £22,430 is taxed at the 20% basic rate, which is £4,486 of income tax; GOV.UK uses the same 20% on £22,430 as its own example. Class 4 National Insurance is 6% of the same £22,430, which is £1,345.80. The bill for 2026/27 is £5,831.80, an effective rate of 16.66%. In Scotland the income tax is £4,501.07: £3,967 at the 19% starter rate, the next £12,989 at 20% and the last £5,474 at the 21% intermediate rate, so the bill is £5,846.87. National Insurance is the same in every part of the UK. All of this assumes the business is your only income; wages, a pension or rent use up the allowance and bands first.

What National Insurance does a sole trader pay?

Class 4, at 6% on profits between £12,570 and £50,270 and 2% on profits above £50,270. Class 2 has not been payable since 6 April 2024. With profits of £7,105 or more in 2026/27 it is treated as paid, so the year counts towards your State Pension and some benefits without you paying anything. Below £7,105 nothing is due, but you can choose to pay voluntary Class 2 at £3.65 a week, £189.80 for the year, to keep the year on your National Insurance record. Tick the box above to add it to the bill.

Why does each £1,000 cost more between £100,000 and £125,140?

Your personal allowance falls by £1 for every £2 of adjusted net income above £100,000, so at £110,000 it is £7,570 and at £125,140 it is gone. In that range each extra £1,000 of profit is taxed at 40% and also removes £500 of allowance, which is then taxed at 40% too: £600 of income tax and £20 of Class 4, so £620 in every £1,000. In Scotland the 45% advanced rate applies there, so it is £695. Pension contributions and Gift Aid donations reduce adjusted net income and can bring some of the allowance back; this calculator does not take them off.

What are payments on account?

Two advance payments towards next year's bill, each half of this year's income tax and Class 4, due on 31 January and 31 July. You do not make them if that tax was less than £1,000, or if more than 80% of the tax you owed was paid outside Self Assessment, for example through your tax code; this calculator assumes the 80% rule does not apply. They make the first January expensive: with £35,000 of profit and nothing paid in advance, you pay the £5,831.80 for 2026/27 plus a first payment on account of £2,915.90 towards 2027/28, so £8,747.70 by 31 January 2028, then £2,915.90 by 31 July 2028. GOV.UK's own example is a £3,000 bill with £1,800 already paid on account: a £1,200 balancing payment plus £1,500 on account, so £2,700 in January and £1,500 in July. If you expect your next bill to be lower, you can ask HMRC to reduce your payments on account.

When do I file and pay for 2026/27?

If you have not sent a tax return before, register for Self Assessment by 5 October 2027. A paper return must reach HMRC by 31 October 2027; an online return is due by 31 January 2028. Pay what you owe for 2026/27, with any first payment on account for 2027/28, by 31 January 2028, and the second payment on account by 31 July 2028. A late return or a late payment brings penalties and interest, even when there turns out to be little tax to pay.

Rates checked 10 November 2026 against GOV.UK "Income Tax rates and Personal Allowances", "Income Tax in Scotland", HMRC's "Income Tax rates and allowances for current and past years", "Rates and allowances: National Insurance contributions", "Self-employed National Insurance rates", "Understand your Self Assessment tax bill" and "Self Assessment tax returns". Not covered: other income, student loan repayments, the High Income Child Benefit Charge, pension and Gift Aid relief, losses and partnerships. This is general information, not tax advice. See GOV.UK: Income Tax rates, Income Tax in Scotland, Self-employed National Insurance rates and Payments on account.