It goes without saying that meeting the tax deadline is important, and you should do everything you can to file your taxes before 31st January. If you fail to meet this deadline then HMRC will penalise you, unless you have a ‘reasonable excuse’. Understandably, HMRC won’t accept any excuse; the taxman is unlikely to accept ‘I forgot to do it’ or ‘I didn’t know when the tax deadline was.’ Reasonable excuses Firstly, let’s start with some examples of reasonable excuses. If an unusual event beyond your control prevents you from filing your tax return, this counts as a ‘reasonable excuse.’ For example: HMRC online failure a faulty laptop serious illnesses, disability and/or serious mental health conditions which prevent you from filing your tax return registering with HMRC in time but not receiving your activation code. These are just a few examples, but if you think you have a reasonable excuse for filing a late tax return, you should contact HMRC as soon as possible. Unreasonable excuses As you would expect, HMRC will not accept a claim if you have an unreasonable excuse for missing the deadline. Here are a few unreasonable excuses: I found the whole process too confusing, I thought my accountant was doing it, I registered with HMRC too late. If you think you have a valid and reasonable excuse for late submission, then you should contact HMRC as soon as possible. You will need to fill in a reasonable excuse claim form, available to download here.     Other Keywords: extension; impossible; cannot finish; period; time; days; penalty