Self Assessment Tax Calculator
Estimate your self assessment tax bill based on self-employed income, allowable expenses, other income and your tax rates.
Overview
Use this self assessment tax calculator to estimate your annual tax bill from self-employed income. Enter your income, allowable expenses, other taxable income, personal allowance, tax rates and any tax already paid to see an estimated balance due.
How it works
The calculator first works out your net self-employed profit by subtracting allowable expenses from self-employed income. It then adds any other taxable income, subtracts your personal allowance and applies your chosen income tax rate to estimate income tax. A separate self-employment tax rate is applied to your net self-employed profit. Finally, any tax already paid is deducted to estimate the remaining balance due.
How to use this calculator
- 1Enter your annual self-employed income before expenses.
- 2Add your allowable business expenses for the tax year.
- 3Include any other taxable income you received.
- 4Enter your personal allowance and the tax rates you want to use.
- 5Add any tax already paid, then review the estimated balance due.
Example Calculation
Self-employed income
$50,000
Allowable expenses
$8,000
Other taxable income
$5,000
Personal allowance
$12,570
Income tax rate
20%
Self-employment tax rate
9%
Tax already paid
$2,000
Estimated balance due
$8,666
If you earn £50,000 from self-employment, claim £8,000 of expenses, have £5,000 of other income, use a £12,570 allowance, apply 20% income tax and 9% self-employment tax, and have already paid £2,000, the estimated balance due is about £10,318.
Frequently asked questions
What does this self assessment tax calculator estimate?
It estimates your taxable income, total tax, and remaining balance due using your self-employed income, expenses, other income, allowances and rates.
Does this calculator use official tax bands automatically?
No. This version is a simplified calculator that uses the income tax rate and self-employment tax rate you enter.
Should I include business expenses?
Yes. Enter allowable expenses so the calculator can reduce your self-employed income to a net profit before estimating tax.
Can I include income from employment or pensions?
Yes. Add other taxable income in the other income field to include it in the estimate.
What should I enter for tax already paid?
Enter any tax you have already paid during the year, such as withholding or payments on account, so the calculator can estimate what may still be due.
Why is this only an estimate?
Actual self assessment bills can depend on tax bands, reliefs, allowances, pension contributions, losses, dividends, and location-specific rules that are not fully modelled here.
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Assumptions and warnings
Assumptions
- This calculator gives a simplified estimate based on the rates and allowance you enter.
- Allowable expenses are deducted from self-employed income before tax is estimated.
- A single income tax rate is applied to all taxable income after the personal allowance.
- The self-employment tax rate is entered by the user and may represent National Insurance style charges or a simplified self-employment tax estimate.
- Tax already paid is deducted from the estimated total tax bill.
Warnings
- This calculator provides an estimate only and is not tax advice.
- Tax rules, thresholds and allowances can change and may vary by tax year and location.
- Check current official guidance or speak to a qualified tax professional for advice on your circumstances.