Self Assessment deadline 2027: all the key dates

If you need to send a tax return for the tax year that ended on 5 April 2026, the main online filing deadline is 31 January 2027. That is the date most people mean when they search for the Self Assessment deadline. Miss it and HMRC can charge late-filing penalties, with interest on any tax paid late. Paper returns usually have an earlier deadline in the previous October. Payments on account fall on 31 January and 31 July — the July payment relates to the tax year you are currently in, not the return due in January. The dates below are computed from GOV.UK guidance and update automatically as the calendar moves. Always confirm against the official source before you act. This page is information, not personal tax advice.