Self Assessment Tax Calculator
Enter your expected self-employment profit for the tax year and this calculator gives you an instant estimate of the Income Tax and Class 4 National Insurance you're likely to owe, along with roughly how much you'd have left.
It's built for a quick, ballpark answer while you're planning ahead — putting money aside during the year, deciding whether a big expense is worth it before year end, or just getting a feel for what January might look like. It isn't a substitute for an actual Self Assessment return, and it doesn't account for things like other income, pension contributions, Marriage Allowance or student loan repayments. If your situation is anything beyond straightforward, a Self Assessment specialist can give you an exact figure.
Profit means your income after allowable business expenses, not your total turnover.
Estimated result
£32,868
estimated left after tax & National Insurance
Rates & assumptions used
- Personal Allowance: £12,570, tapered above £100,000 profit
- Basic rate: 20% up to £50,270
- Higher rate: 40% up to £125,140
- Additional rate: 45% above £125,140
- Class 4 National Insurance: 6% between £12,570 and £50,270, 2% above
- Assumes England, Wales or Northern Ireland rates — Scottish Income Tax bands differ
- Assumes this profit is your only taxable income for the year
Where your profit goes
- Personal Allowance applied
- £12,570
- Taxed at 20% (basic rate)
- £5,486
- Income Tax
- £5,486
- Class 4 National Insurance
- £1,646
- Total tax & National Insurance
- £7,132
- Effective rate
- 17.8%
This is an estimate for planning purposes only, not a tax return or financial advice. It assumes this profit is your only taxable income for the year.
For the full picture, see our first-time Self Assessment guide, or head straight to Self Assessment support.
How this calculator works
- 1Enter your expected self-employment profit for the tax year — that's your income after allowable business expenses, not your turnover.
- 2The calculator applies the current Personal Allowance, tapering it away if your profit is over £100,000.
- 3Income Tax is worked out using the standard basic, higher and additional rate bands for England, Wales and Northern Ireland.
- 4Class 4 National Insurance is calculated on your profit between the Lower and Upper Profits Limits, plus a lower rate above that.
- 5Everything updates instantly as you type — there's nothing to submit and nothing is saved or sent anywhere.
FAQs
Self Assessment Tax Calculator questions
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