How do I challenge or appeal a Self Assessment penalty from HMRC?

Full answer

If HMRC issues a Self Assessment penalty — commonly the automatic £100 late filing penalty for missing the 31 January deadline, daily penalties after three months, additional percentage-based penalties after six and twelve months, or late payment penalties calculated as a percentage of tax owed — you have the right to formally appeal within 30 days of the date on the penalty notice, provided you have a genuine reasonable excuse for the failure. The appeal can be made online through your HMRC personal tax account (generally the quickest route) or by post using form SA370 for penalty appeals, and must set out clearly what happened, when it happened, and why it prevented you from filing or paying on time, along with any supporting evidence such as medical documentation, evidence of a computer or software failure, or evidence of a genuinely unforeseen and unavoidable event. If HMRC rejects your appeal, you have two further options: you can request an independent internal review by a different HMRC officer who was not involved in the original decision (a relatively quick, free process), or you can appeal directly to the independent tax tribunal, which is separate from HMRC entirely and can overturn HMRC's decision if it finds in your favour, though this is a more formal process typically reserved for cases where the amounts involved or the principle at stake justify the additional time and effort. It is important to note that simply appealing a penalty does not automatically pause the requirement to pay the underlying tax owed or stop further late payment penalties or interest accruing on unpaid tax in the meantime — the appeal relates specifically to the penalty itself, not the tax liability, unless you separately dispute the tax calculation too. Even if your reasonable excuse appeal is unsuccessful, you may still be able to negotiate a Time to Pay arrangement with HMRC to spread payment of the tax and any confirmed penalty over instalments, which is a separate process from disputing whether the penalty was fairly charged in the first place. Use the Self-Employed Tax calculator to check your underlying tax position while resolving any penalty dispute.

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More answers

• What counts as a reasonable excuse for a late Self Assessment tax return?