Self-employed tax calculator 2026/27

Enter your sales and allowable expenses to estimate the income tax and Class 4 National Insurance on your profit – and how much to put aside each month for your Self Assessment bill.

Estimate only – not financial or tax advice. Tax year: 2026/27. Source: GOV.UK income tax rates, GOV.UK self-employed NI, GOV.UK trading allowance, gov.scot Scottish rates. Figures last checked: . Does not include payments on account, student loan, pension or capital allowances.

How self-employed tax is worked out

As a sole trader you pay tax on your profit: what you earned from the business minus your allowable business expenses. Two things are due on that profit through Self Assessment:

  • Income tax at the same rates as an employee. The first £12,570 of your total income is usually tax-free, then 20%, 40% and 45% in England, Wales and Northern Ireland, or the six Scottish rates if you live in Scotland.
  • Class 4 National Insurance: 6% on profits between £12,570 and £50,270, and 2% above £50,270.

Class 2 National Insurance is no longer charged on profits above the small profits threshold – you get the credit for your State Pension automatically. If your profit is under £7,105 you can choose to pay voluntary Class 2 to protect your State Pension record.

Expenses or the trading allowance

You can deduct allowable expenses (stock, tools, software, phone and internet for the business, a share of travel and vehicle costs, accountant's fees and so on), or claim the £1,000 trading allowance instead – whichever is higher. Tick “Use the £1,000 trading allowance if it is better” and the calculator picks the better one for you.

If you also have a job

Put your salary from employment under “Other taxable income”. Your Personal Allowance and the basic-rate band are used by that income first, so the calculator shows only the extra income tax caused by your profit. Class 4 National Insurance is worked out on the profit alone.

Worked example

Sales £40,000, expenses £10,000, no other income, England:

  • Profit: £40,000 − £10,000 = £30,000
  • Income tax: (£30,000 − £12,570) × 20% = £3,486
  • Class 4 NI: (£30,000 − £12,570) × 6% = £1,045.80
  • Total to pay: £4,531.80 – about £377.65 to set aside each month.

When you pay

The Self Assessment tax return and the balance of your bill are due by 31 January after the end of the tax year. If your bill is over £1,000 you will usually also make two payments on account towards next year's bill (31 January and 31 July), each half of this year's bill – which is why the first year can feel expensive. This calculator does not add payments on account.

Frequently asked questions

How much tax do I pay on £30,000 self-employed profit?

In England in 2026/27, about £3,486 income tax and £1,045.80 Class 4 National Insurance – £4,531.80 in total, if you have no other income.

Do I still pay Class 2 National Insurance?

Not if your profit is above the small profits threshold – you get the State Pension credit automatically. Below £7,105 profit you can pay voluntary Class 2 (£3.65 a week in 2026/27).

Can I claim expenses and the £1,000 trading allowance?

No – it is one or the other for your trading income. Claim the trading allowance only if it is more than your actual expenses.

How much should I save for tax?

Set aside the “to set aside each month” figure. Many sole traders save 25–30% of profit as a rough rule, but the calculator gives you a figure based on your own numbers.