Self-Assessment is the system HMRC uses for individuals and sole traders to report income and calculate tax that is not automatically deducted through PAYE. Anyone who is self-employed, a company director, a landlord, or has other untaxed income above certain thresholds must usually register for Self-Assessment and file an annual tax return.
Why Self-Assessment matters
The Self-Assessment return covers income from self-employment, property, dividends, savings interest, and capital gains, alongside details of allowable expenses and reliefs claimed. The deadline for online returns is 31 January following the end of the tax year, which is also when any tax owed must be paid, alongside the first payment on account for the following year where applicable.
Penalties for late filing
HMRC issues an automatic penalty for missing the filing deadline, even if no tax is owed, with further penalties accruing the longer a return remains outstanding. Keeping accurate records throughout the year makes it much easier to file on time and avoid unnecessary penalties.
Tax rules depend on individual circumstances and can change. This glossary is general information rather than personalised tax advice.