There are a number of options open to taxpayers who disagree with a tax decision issued by HMRC. As a first step, it may be possible to make an appeal against a tax decision. There is normally a 30-day deadline for making a claim, so time is of the essence. HMRC will then carry out a review, usually by using HMRC officers that were not involved in the original decision. A response to an appeal is usually made within 45 days but can take longer for complex issues. In certain cases, it is possible to appeal against penalties on the grounds of having what is known as a 'reasonable excuse'. HMRC’s guidance lists the following examples of what may count as a reasonable excuse: 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 HMRC online services a fire, flood or theft prevented you from completing your tax return postal delays that you couldn’t have predicted delays related to a disability you have However, not receiving a reminder, relying on someone else or making a mistake are amongst the reasons not counted as reasonable excuses.