Self Assessment is a system HM Revenue and Customs uses to collect Income Tax, deadlines and penalties apply.
If you're new to Self Assessment, you'll need to keep records (for example bank statements or receipts) so you can fill in your tax return correctly.
If you've been told to send a return:
If you get an email or letter from HM Revenue and Customs (HMRC) telling you to send a return, you must send it - even if you don't have any tax to pay.
If you used to send a tax return but don't need to send one for the last tax year, you can contact HMRC to close your Self Assessment account.
You must also tell HMRC if you've stopped being self-employed.