What happens if you miss the Self Assessment deadline?

Full answer

Missing the Self Assessment filing deadline (31 January for online returns) triggers an escalating penalty structure from HMRC. **Penalty ladder — late filing:** | Time overdue | Penalty | |---|---| | From **1 February** (day 1) | **£100 automatic penalty** (even if no tax is owed) | | 3 months late (1 May+) | **£10 per day** for up to 90 days (max £900) | | 6 months late (31 July+) | **£300 or 5% of tax owed**, whichever is higher | | 12 months late (31 January next year+) | A further **£300 or 5% of tax owed** (higher) — in serious cases can be up to 100% of tax due | **Late payment interest:** From 31 January 2027, unpaid tax accrues interest at **HMRC's late payment rate — currently 7.5%** (Bank of England base rate + 2.5%). **Late payment penalties (separate from filing):** - 30 days late: 5% of unpaid tax - 6 months late: further 5% - 12 months late: further 5% These stack on top of the interest charge. **How to appeal — reasonable excuse:** You can appeal penalties if you have a "reasonable excuse" — HMRC accepts: serious illness, death of a close relative, postal failure (HMRC's fault), software failure, or natural disaster. The excuse must have prevented filing, not just made it inconvenient. Appeal within **30 days** of the penalty notice. **HMRC Time to Pay:** If you cannot pay your tax bill, set up a **Time to Pay arrangement** online (for bills up to £30,000) or by calling the HMRC payment helpline (0300 200 3835). Interest still accrues, but penalties are suspended if you stick to the arrangement. **Late filing vs late payment:** These are separate penalty regimes. You can file on time but pay late (accruing payment penalties + interest) — or pay an estimate on time and file late (accruing filing penalties). Always file even if you cannot pay — filing penalties are additional to payment penalties.

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