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.

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.

UK rates for the 2026/27 tax year · last checked against GOV.UK on 6 April 2026

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.

Rates and sources

This calculator uses UK rates for the 2026/27 tax year, last checked against GOV.UK on 6 April 2026.

Self Assessment tax returns — official guidance:

gov.uk/self-assessment-tax-returns

Rates change, usually at the start of a tax year in April. Always confirm against GOV.UK before relying on a figure for a filing or a financial decision.

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.