Money Worked Out

Self-employed tax calculator

Enter your profit for the 2026/27 tax year, and any pay from a job, to see the income tax, National Insurance and student loan your profit adds. The result shows how much that comes to each month, to put aside for your Self Assessment bill.

Set aside for tax a month

£594.32

£32,868.20 of your £40,000.00 profit is yours to keep

Your details

Income tax on profit
£5,486.00
Class 4 National Insurance
£1,645.80
Student loan on profit
£0.00
Set aside for the year
£7,131.80
How this was worked out
  1. Tax year 2026/27; England, Wales and Northern Ireland income tax; annual calculation.
  2. Job income plus profit: £0.00 + £40,000.00 = £40,000.00.
  3. Personal allowance after any taper: £12,570.00.
  4. Income tax on both sources minus income tax on the job alone: £5,486.00 − £0.00 = £5,486.00.
  5. Class 4 National Insurance on profit: £1,645.80.
  6. Class 2 is not compulsory in 2026/27; voluntary payments are not included.
  7. Extra student loan repayment caused by profit: £0.00.
  8. Profit minus income tax, Class 4 and student loan: £32,868.20.
  9. Payments on account may apply if last year's income tax and Class 4 bill was at least £1,000.00, unless more than 80% of the tax was paid outside Self Assessment. Student loan repayments are excluded. Each payment is normally half the previous year's bill.
  10. Estimate only. Other taxable income, reliefs, deductions and National Insurance restrictions can change the final bill. This is information, not advice.

What the calculator assumes

Income tax on your profit

HMRC adds your profit to any pay from a job and charges income tax on the total. In England, Wales and Northern Ireland the first £37,700 of taxable income is taxed at 20%, then 40% up to £125,140, and 45% above that. If you live in Scotland, choose Scotland and the calculator uses the Scottish bands, which run from 19% to 48%.

To find the tax on the profit alone, the calculator works out the tax on your job pay by itself and then the tax on job pay and profit together. The difference is what the profit costs you in income tax. If you have a job, the profit starts in whatever band your pay has already reached, so a side business can be taxed at the higher rate from its first pound.

Once your total income passes £100,000, your personal allowance goes down by 50% of the income above that point. The calculator includes this when your figures reach it.

National Insurance when you work for yourself

Self-employed people pay Class 4 National Insurance on their profit. It is charged at a main rate on profit between a lower and an upper limit, and at a smaller rate on profit above the upper limit. Pay from a job does not count towards Class 4. That pay has its own National Insurance, which comes out through payroll. The working under the result shows the Class 4 limits and rates for 2026/27.

Class 2 National Insurance costs most self-employed people nothing. If your profit is above a small profits threshold, Class 2 is treated as paid, which protects your National Insurance record without any charge. Below that threshold you pay nothing, but you can choose to pay Class 2 voluntarily to fill the year on your record. So the calculator shows no Class 2 in the result. The National Insurance rates page sets out the rates for employees next to these.

Student loan

If you have a student loan, HMRC works out what you owe from your Self Assessment return, using your profit and any job pay added together for the whole year. You repay a share of that combined income above your plan's yearly threshold. If your employer has already taken repayments from your salary, HMRC takes them off what you owe. The student loan repayment calculator lists each plan's threshold and rate.

When the bill is due

You send a Self Assessment return after the tax year ends. For an online return, the return and any balance still owed are due by 31 January after the tax year ends.

HMRC may also ask for payments on account. These are two advance payments towards next year's bill, each half of the bill you have just had, due on 31 January and 31 July. They cover income tax and Class 4. Student loan repayments are paid with the January balance instead. You do not have to make payments on account if last year's bill was below a set limit, or if more than a set share of last year's tax was already collected another way, for example through your tax code. When your figures pass that limit, the calculator adds a line about it to the working.

Your first January can be the largest payment. If you have not made payments on account before, you pay the whole bill for the year plus the first payment on account for the next year, both on the same date. The monthly figure in the result is the bill for one year divided by twelve, so it does not include payments on account.

What it leaves out

If you also have a job, the take-home pay calculator shows what your salary leaves you on its own. Contractors who work through their own limited company can use the IR35 calculator instead. The income tax rates page lists every band for the year.

Official guidance

Report a mistake

We will receive the page address and the tax year. We will not receive the figures you entered.

Please do not include your name or contact details. To get a reply, email [email protected] instead.

Spotted a mistake?

Email [email protected]. Tell us what you entered and what you expected to see. Fixed errors are listed on the corrections page.