HMRC Self Assessment Penalty Calculator
Calculate penalties and interest for a late Self Assessment tax return under current HMRC rules. Covers the £100 automatic penalty, daily charges, and the 6-month and 12-month surcharges.
About Self Assessment penalties
How much is the HMRC penalty for a late Self Assessment return?▾
The HMRC penalty for a late Self Assessment return starts with an automatic £100 fine on day 1 — even if you owe no tax. After 3 months, £10 daily penalties apply for up to 90 days (maximum £900). At 6 months, a further penalty of 5% of tax owed or £300 (whichever is greater) is charged. A further 5% or £300 is added at 12 months.
Do I still get a penalty if I owe no tax?▾
Yes. The initial £100 Self Assessment late filing penalty applies regardless of whether any tax is owed. You must still file your return, even if your tax bill is zero.
What is the deadline for Self Assessment?▾
The online Self Assessment deadline is 31 January each year. The paper return deadline is 31 October. For example, returns for the 2024/25 tax year are due by 31 January 2026 (online) or 31 October 2025 (paper).
Can I appeal a Self Assessment penalty?▾
Yes — if you have a genuine reasonable excuse for filing late (such as serious illness, bereavement, or an HMRC technical failure), you can appeal within 30 days of receiving the penalty notice. A tax specialist can assess your grounds and submit the appeal on your behalf.