UK Self Assessment 2026: Deadlines, Tax Return Dates & HMRC Filing Guide
For the 2025 to 26 UK tax year, the main Self Assessment deadlines are 5 October 2026 to register (if required), 31 October 2026 for paper tax returns and 31 January 2027 for online tax returns and paying any tax owed. Missing these deadlines may result in HMRC penalties and interest. Knowing these key dates…