DateWhat
5 October 2026Tell HMRC you need a return if you are new to Self Assessment
31 October 2026Paper return deadline
30 December 2026File online if you want the bill collected through a PAYE tax code
31 January 2027Online return and balancing payment
31 July 2027Second Payment on Account (if you make them)

Open the full calendar with penalties and Payment on Account explained.