If you’re registered for Self Assessment, you’ll usually get a letter in April or May from HM Revenue and Customs (HMRC) telling you to send a tax return. You should send your tax return, even if you don’t have any tax to pay.
How and when to send your tax return
You can send your tax return online or using paper forms but you must be registered for Self Assessment.
You can hire a professional (eg an accountant) to help you with your tax return.