Self-Assessment Tax Returns Self-Assessment Tax Returns for the year ended 5th April 2016 MUST be submitted online to HM Revenue & Customs at the very latest by 31 January 2017. Automatic £100 penalty fines are issued from HM Revenue & Customs for any Tax Return not filed by the deadline date. This is irrespective of there being any tax due. Additional penalties can also be charged, including daily penalties. If you haven’t done so already then please do let us have the req