Self-employed tax calculator

Work out the Income Tax, Class 4 National Insurance and student loan on your self-employed profit, how much to put aside each month, and whether you'll need payments on account.

How this calculator works

It follows the same steps as your Self Assessment tax return, using HMRC's rates for the tax year you pick. The 2025/26 tax year ran from 6 April 2025 to 5 April 2026, and its return and tax are due by 31 January 2027. The 2026/27 year runs from 6 April 2026 to 5 April 2027, due by 31 January 2028.

• Profit. Your turnover minus your allowable expenses. Instead of expenses you can take the £1,000 trading allowance, but not both. If your expenses are more than your turnover you've made a loss, and the calculator counts your profit as zero.
• Income Tax. Your profit and any employment income are added together. The first £12,570 is your tax-free Personal Allowance, which shrinks by £1 for every £2 of income over £100,000 and is gone at £125,140. Above it, England, Wales and Northern Ireland charge 20%, 40% and 45%, and Scotland has six bands from 19% to 48%. Tax already taken from your job through PAYE comes off, so only the rest is due through Self Assessment.
• Class 4 National Insurance. 6% on profits between £12,570 and £50,270 and 2% above, in both years. It's charged on your self-employed profit only, not your wages.
• Class 2 National Insurance. Since 6 April 2024 you don't have to pay it. If your profit is at least the small profits threshold (£6,845 in 2025/26, £7,105 in 2026/27) you get the State Pension credit anyway. Below it you can choose to pay voluntarily (£3.50 a week in 2025/26, £3.65 in 2026/27) to protect your State Pension record.
• Student loans. 9% of your total income above your plan's threshold, or 6% above £21,000 for a Postgraduate Loan. Anything already taken from your wages comes off. The thresholds change each year, and Plan 5 repayments only start in 2026/27.
• Pension. Money you pay into a personal pension has 20% basic rate relief added by your provider, so £80 becomes £100 in your pension. That gross amount widens your basic rate band, which gives higher and additional rate taxpayers their extra relief through the tax return, and it lowers the income used for the £100,000 taper.
• Payments on account. If your Self Assessment bill (Income Tax and Class 4, not student loan) is £1,000 or more and less than 80% of your tax was taken at source, HMRC asks for two advance payments towards next year, each half of this year's bill, due on 31 January and 31 July.

The monthly figure is the Self Assessment bill divided by 12, so you can move that amount to a savings account each month. It doesn't include payments on account, which are covered below it.

Tips for setting tax aside

• Use a separate savings account. Move the monthly amount out as soon as you're paid, ideally into an easy-access account that pays interest, so it's there in January.
• Plan for your first January. In your first year with payments on account you pay the whole bill for last year plus the first payment on account for this year on the same day. That can be one and a half times your normal yearly bill.
• Keep records of every expense. Things like equipment, mileage, phone, software and a share of home costs can all come off your profit. Our mileage allowance calculator shows HMRC's approved mileage rates.
• Expecting a lower profit next year? You can ask HMRC to reduce your payments on account, in your online account or on form SA303. If you reduce them too far you'll pay interest on the difference.
• Also employed? Use the take-home pay calculator to see what your job pays after tax, then add this bill on top.

Frequently asked questions

Which tax year should I choose?

Choose 2025/26 if you're filling in the tax return due by 31 January 2027. That covers what you earned from 6 April 2025 to 5 April 2026. Choose 2026/27 to estimate the tax on what you're earning now, which you'll pay by 31 January 2028.

How much should I set aside for tax when self-employed?

It depends on your profit. A common rule of thumb is 20% to 30% of your profit, but the calculator gives you an exact figure and percentage. With a profit of £30,000 and no other income, it's about £4,530 for 2025/26, around 15% of your profit or £378 a month.

Do I have to pay Class 2 National Insurance?

No, not since 6 April 2024. If your profit is above the small profits threshold you're treated as having paid it, so it still counts towards your State Pension. If your profit is lower you can pay it voluntarily, which is much cheaper than Class 3 voluntary contributions.

Should I use the £1,000 trading allowance or my expenses?

Use whichever takes more off your profit. If your expenses are under £1,000 the trading allowance is usually better. You can't claim both. If your turnover is £1,000 or less, the allowance covers it all and you usually don't need to tell HMRC about it.

What are payments on account?

Advance payments towards next year's tax. Each is half of this year's Income Tax and Class 4 bill, paid on 31 January and 31 July. When you file next year's return, what you've paid in advance comes off. You don't have to make them if your bill was under £1,000, or if more than 80% of your tax was already taken through PAYE.

What if I made a loss?

The calculator shows a profit of zero. A trading loss can usually be carried forward against future profits from the same business, or set against other income in the same or previous year. Check HMRC's guidance on trading losses or ask an accountant.

Does it work out tax on savings, dividends or property?

No. It covers self-employed profit and employment income only. Savings interest, dividends, rental income and capital gains have their own allowances and rates, so add those on your tax return.

Is this tax advice?

No. It's an estimate to help you plan. It assumes you're under State Pension age (Class 4 stops after that), your employment income was taxed with the standard 1257L tax code, and you have no other income or reliefs.

Results are estimates for illustration only and aren't financial or tax advice. Rates from GOV.UK (2025/26 and 2026/27 thresholds, self-employed National Insurance, payments on account) and gov.scot (2025/26 and 2026/27 Scottish bands), checked 6 November 2026.