Reasonable excuses

You can appeal against some penalties if you have a reasonable excuse, for example for your return or payment being late.

What may count as a reasonable excuse

A reasonable excuse is something that stopped you meeting a tax obligation that you took reasonable care to meet, for example:

• your partner or another close relative died shortly before the tax return or payment deadline
• you had an unexpected stay in hospital that prevented you from dealing with your tax affairs
• you had a serious or life-threatening illness
• your computer or software failed just before or while you were preparing your online return
• service issues with HM Revenue and Customs (HMRC) online services
• a fire, flood or theft prevented you from completing your tax return
• postal delays that you could not have predicted
• delays related to a disability you have

You must send your return or payment as soon as possible after your reasonable excuse is resolved.

What will not count as a reasonable excuse

The following will not be accepted as a reasonable excuse:

• you relied on someone else to send your return and they did not
• your cheque bounced or payment failed because you did not have enough money
• you found the HMRC online system too difficult to use
• you did not get a reminder from HMRC
• you made a mistake on your tax return

source: https://www.gov.uk/tax-appeals/reasonable-excuses