Self Assessment tax calculator
Self Assessment Tax Calculator UK
Estimate your UK self-employed Income Tax, National Insurance and take-home income with PoundKit's Self Assessment tax calculator.
Scottish Income Tax bands are different and are not included in this version of the calculator.
£11,788.60
Income Tax £9,432.00 + Class 4 NI £2,356.60
£43,211.40
Profit minus estimated tax
Breakdown
- Business income
- £60,000.00
- Business expenses
- −£5,000.00
- Estimated profit
- £55,000.00
- Taxable income (after allowance)
- £42,430.00
- Income Tax estimate
- £9,432.00
- Class 4 National Insurance
- £2,356.60
- Total estimated tax
- £11,788.60
Tax reserve recommendation
Set aside approximately £982.38 per month to cover your estimated tax bill.
Estimate only. This tool is not a tax filing service and does not account for payments on account, student loans, pension contributions, Gift Aid, marriage allowance or other reliefs.
Self Assessment Tax Calculator
Self Assessment tax estimates how much Income Tax and National Insurance a UK freelancer or sole trader may owe based on taxable profit.
This calculator provides an estimate only. Tax rules change and your final tax position depends on your circumstances.
Example: UK freelancer earning £60,000
A freelancer invoices £60,000 in a tax year and claims £5,000 of allowable business expenses, leaving a taxable profit of £55,000.
- Income
- £60,000.00
- Expenses
- £5,000.00
- Profit
- £55,000.00
- Estimated tax
- £11,788.60
- Estimated take-home
- £43,211.40
- Monthly tax reserve
- £982.38
Example values are for illustration only.
How Self Assessment tax is estimated
The estimate considers:
- Business profit — business income minus allowable expenses.
- Personal Allowance — the amount of income you can earn before Income Tax applies, tapered above £100,000.
- Income Tax bands — basic, higher and additional rates applied to taxable income.
- Class 4 National Insurance — a percentage of self-employed profits between the lower and upper profits limits, plus a smaller percentage above the upper limit.
profit = businessIncome − businessExpenses
taxableIncome = max(0, profit + otherIncome − personalAllowance)
incomeTax = tax across basic / higher / additional bands
class4NI = 6% of profits £12,570–£50,270 + 2% above
totalTax = incomeTax + class4NI
takeHome = profit + otherIncome − totalTax
monthlyReserve = totalTax ÷ 12
Tax bands and allowances depend on the tax year and location.
Editorial review
Last reviewed .
Official guidance checked:
- GOV.UK — Income Tax rates (opens in a new tab)
- GOV.UK — Self-employed National Insurance rates (opens in a new tab)
- GOV.UK — Self Assessment tax returns (opens in a new tab)
Calculation logic reviewed .
Information only — not tax or legal advice. Always check current guidance on GOV.UK for your situation.
How this calculator works
PoundKit publishes the calculation logic and automated tests behind its business calculators.
Questions
What is Self Assessment tax?
Self Assessment is the system HMRC uses to collect Income Tax from people whose tax is not deducted automatically, such as freelancers and sole traders. You report your income and allowable expenses in a tax return each year, and HMRC calculates what you owe based on that return.How much tax does a sole trader pay in the UK?
It depends on your taxable profit. Sole traders pay Income Tax on profits above the Personal Allowance at 20%, 40% or 45% depending on the band, plus Class 4 National Insurance on profits above the lower profits limit. For example, a £55,000 profit produces an estimated £11,788.60 in combined Income Tax and Class 4 NI in 2026/27.How do freelancers calculate tax?
Start with business income, subtract allowable business expenses to get taxable profit, then apply the Personal Allowance and Income Tax bands. Add Class 4 National Insurance on profits. PoundKit's calculator automates this estimate — enter income and expenses above to see the breakdown.How much should freelancers save for tax?
A common rule of thumb is to set aside 25–30% of your profit each month. This calculator shows a monthly tax reserve figure — your estimated annual tax bill divided by 12 — so you can move that amount into a separate savings account as you get paid.
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