Self Assessment Tax Bill Calculator
Estimate your total self assessment liability for 2026/27 including income tax, Class 4 National Insurance contributions, and any Capital Gains Tax due.
How it's calculated
Total bill = Income Tax + Class 4 NI + CGT. Payments on account (50% of prior year liability) are typically due 31 January and 31 July.
Frequently Asked Questions
- Who needs to complete a self assessment tax return?
- You need to file if you are self-employed with profits over £1,000, a company director, have income over £100,000, received more than £2,500 in rental income, or have tax to pay that cannot be collected through PAYE.
- When is the self assessment deadline?
- Online returns must be filed by 31 January following the end of the tax year. Any tax owed must also be paid by 31 January. A payment on account may be due 31 July.
- What are payments on account?
- If your self assessment bill is over £1,000, HMRC requires advance payments (payments on account) of 50% of the prior year's bill, due 31 January and 31 July. This calculator shows your estimated annual liability before payments on account.