Some taxpayers will be unable to file their Self Assessment returns online for the year ended 5 April 2026 due to software specification issues from HMRC. A list of filing exclusions for individuals has recently been published by HMRC.
Where a particular case is on the list of online filing exclusions, you cannot file online and must complete a paper tax return by 31 January 2027.
Where a paper return has not been filed by 31 October 2026, a Reasonable excuse appeal form must accompany the return to avoid Late filing penalties. Remember that paper returns still need an actual signature.
As well as online filing exclusions, HMRC list several special cases where they have identified issues requiring a workaround to prevent a filing rejection. Most of these workarounds should have been incorporated into filing software, but in some cases, a paper return may be required.
Useful guides on this topic
Grounds for Appeal: Reasonable excuse
What is considered to be a 'reasonable excuse' when a taxpayer makes an appeal against a tax compliance failure?
External links
HMRC: Self Assessment technical specifications (2026) for individual returns
HMRC: Self Assessment technical specifications (2026) for partnership returns
HMRC: Self Assessment technical specifications (2026) for trust and estate returns