28 January 2025
The acceptable excuses for a late tax return
Over a million taxpayers have failed to submit their tax returns by the 31 January deadline in recent years and if the numbers are similar for the forthcoming deadline, it could lead to a penalty windfall for HMRC in the region of £100m.
Such penalties are issued automatically and taxpayers can seek to appeal them if they have a reasonable excuse. What classifies as reasonable is not always well understood and HMRC has previously published lists of some of the unsuccessful attempts, which included:
- The death of a goldfish.
- A run-in with a cow.
- A wife refusing to give their husband their mail.
- A hamster eating the post.
- A mother-in-law being a witch and placing a curse on them.
Whilst these excuses may liven up an HMRC officer’s day, to be successful a taxpayer will need to show they have taken reasonable care in trying to meet their obligations. Part of the test involves imagining what someone similar to you might have done in the same circumstances if they wanted to meet the deadline. HMRC will consider each individual’s circumstances on their own merits and the comparison to a hypothetical person will be with someone standing in the same shoes.
Individuals suffering from an illness or a mental health condition may have grounds for an appeal against a late filing penalty. However, HMRC’s guidance indicates that simply asserting that you are suffering from a mental health condition is unlikely to be sufficient. A taxpayer will also need to demonstrate how their condition “detrimentally affected their ability to comply with their tax obligation”.
That could involve some difficult questions on what may be a sensitive subject. Taxpayers in these circumstances may therefore want to pre-empt this by sending HMRC evidence at the outset, such as a note from a medical or mental health professional.
Many might assume that the phrase “ignorance of the law is no excuse” applies to late filing penalties as well but that is not necessarily so. The case of Perrin vs HMRC highlighted that ignorance might be a perfectly reasonable excuse in some instances but it will obviously depend on the circumstances. Perhaps unsurprisingly, HMRC’s expectation is that most people should be aware of their tax filing obligations so in practice, relying on a lack of awareness is likely to be challenging.
Ultimately, the clue is in the name and a common sense interpretation of what represents a reasonable excuse is often a good barometer of its chances of success. If your teacher would have raised a quizzical eyebrow at the excuse for a lack of homework, then HMRC is likely to do the same.

