What is Self Assessment?
The process of filing your own tax return with HMRC, typically required for self-employed people and those with complex tax affairs.
Key Facts
- ✓ Required for self-employed, high earners, and those with untaxed income
- ✓ Online filing deadline: 31 January
- ✓ Paper filing deadline: 31 October
- ✓ Tax payment deadline: 31 January
- ✓ Late filing penalty: automatic £100 fine
- ✓ Payments on account if bill exceeds £1,000
Explanation
Self Assessment is the system HMRC uses to collect income tax from people whose tax is not fully collected through PAYE. You must file a Self Assessment tax return if you are self-employed with income over £1,000, earn over £150,000, have untaxed income such as rental income or dividends above the allowance, need to claim certain tax reliefs, or receive the High Income Child Benefit Charge (income over £60,000). The tax return covers the tax year from 6 April to 5 April. The deadline for paper returns is 31 October; 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. If your bill exceeds £1,000, you may need to make payments on account — advance payments towards next year's bill. Late filing incurs automatic penalties starting at £100.
Try the calculator: Use our free calculator to see how self assessment affects your finances.
Self-Employed Tax Calculator →Other Glossary Terms
The system HMRC uses to collect income tax and National Insurance directly from employees' wages.
National InsuranceA UK tax on earnings and self-employed profits that funds the state pension, NHS, and benefits.
Personal AllowanceThe amount of income you can earn each year before paying income tax — currently £12,570.
Basic Rate (20%)The 20% income tax rate applied to taxable income between £12,571 and £50,270.
Higher Rate (40%)The 40% income tax rate applied to taxable income between £50,271 and £125,140.
Additional Rate (45%)The 45% income tax rate applied to taxable income above £125,140.