Self-employed tax calculator 2026/27

Estimate your Self Assessment bill, including Income Tax, National Insurance and payments on account, so you know how much to put aside and when it's due.

Estimate your tax bill

The short answer

You pay Income Tax (20%, 40% or 45%) on profit above the £12,570 personal allowance, plus Class 4 National Insurance (6%, then 2% above £50,270).
The bill for 2026/27 is due on 31 January 2028.
If it's £1,000 or more, you'll usually also pay half of next year's bill in advance on the same day, so your first January payment can be much bigger than expected.

An estimate for sole traders in England, Wales and Northern Ireland using 2026/27 rates. Doesn't include student loans, pension contributions, Scottish tax rates or capital gains. Not tax advice.

How your bill is worked out

Profit: turnover minus allowable business costs.
Income Tax: your profit is added to any other income. Tax is charged at 20% from £12,571 to £50,270, 40% up to £125,140 and 45% above. The £12,570 allowance shrinks once income goes over £100,000.
Class 4 National Insurance: 6% on profits between £12,570 and £50,270, and 2% above that. Class 2 is no longer compulsory.
Payments on account: if your Self Assessment bill is £1,000 or more, HMRC usually asks for two advance payments towards next year, each half of this year's bill.

Why your first bill is often a shock

In your first year of payments on account, the January payment includes this year's full bill plus half of next year's. So a £6,000 bill can mean paying £9,000 in January and another £3,000 in July. After that, it evens out.

Frequently asked questions

How much should I put aside for tax as a sole trader?

A common rule of thumb is 20 to 30% of your profit, more if you're a higher rate taxpayer. Use the calculator for a figure based on your own numbers, and put aside a set amount each month.

When do I pay my tax?

Your 2026/27 bill is due by 31 January 2028. If you make payments on account, they're due on 31 January and 31 July. See all Self Assessment dates.

Do I still pay Class 2 National Insurance?

No, not compulsorily. If your profits are £7,105 or more, you're treated as having paid it. Below that, you can choose to pay voluntarily to protect your State Pension record.

Does Making Tax Digital change when I pay?

No. You send quarterly updates, but the payment dates stay the same. Check if MTD applies to you.

Should I become a limited company?

It can save tax at higher profits, but it adds costs and admin. It's worth talking to an accountant once your profits are consistently high.

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