As for previous years, many taxpayers will be unable to file their Self Assessment returns for the year ended 5 April 2021 online due to software specification issues from HMRC.
The exclusions apply to individuals, partnerships and trustees and personal representatives filing Trust and Estates returns.
If your case is on the list you cannot file online and must complete a paper tax return by 31 January 2022. Unless the return is filed by 31 October 2021, a Reasonable excuse appeal form must accompany the return. Remember that paper returns still need an actual signature.
For Exclusion cases for 2020-21 and earlier years, see HMRC self-assessment technical specifications 2020 for Individuals, for Partnerships and for Trusts and Estates.
Useful guides on this topic
2020/21 Self Assessment Tax Return toolkit
A tax return toolkit for the year ending 5 April 2021.
Grounds for Appeal: Reasonable excuse
What is considered to be a 'reasonable excuse' when a taxpayer makes an appeal against a tax compliance failure?
Self Assessment 2019-20 returns: Online filing exclusions
Online filing exclusions for the 2019-20 tax year