Most people in the UK pay their tax at source, i.e. through Pay As You Earn (PAYE) if they are employed, so are not required to file a tax return. Under Self Assessment you are responsible for completing a tax return if needed and for paying any tax due.
You mention that you are unemployed since January 2019 and have no income. However there are a few other factors you should consider.
For example you might need to complete a Self Assessment if:
- Your total income was more than £100,000 between April 2018 and April 2019
- You received more than £10,000 from dividends or any investments
- You had any income from outside the UK
- You sold or gave away personal possessions worth more than £6,000 (except your car) – therefore you may need to pay Capital Gains Tax
- You held a position which might affect how you are taxed such as religious minister or examiner
If you had no income and any other circumstances that might affect your tax status you probably do not need to complete a Self Assessment. If HMRC has asked you to send a return, do contact them and let them know to withdraw the return in order to avoid paying any fees.
You can contact HMRC to find more info on your case through www.gov.uk