Self-Assessment Late Filing Penalty Calculator 2026
Calculate HMRC self-assessment late filing penalties. £100 fixed penalty on day 1, daily £10 penalties after 3 months (up to £900), 5% surcharges at 6 and 12 months.
Self-Assessment Late Filing Penalty Calculator
The filing deadline for online self-assessment returns is 31 January each year. Miss it and penalties mount quickly.
Frequently Asked Questions
What is the self-assessment filing deadline?
Online self-assessment returns must be filed by 31 January following the end of the tax year (e.g., 31 January 2026 for 2024/25). Paper returns have an earlier deadline of 31 October.
What is the penalty for filing late?
Day 1: £100 fixed penalty. After 3 months (90 days): £10/day for up to 90 days (maximum £900). After 6 months: 5% of tax owed or £300 (whichever is greater). After 12 months: additional 5% or £300.
Can I appeal a late filing penalty?
Yes — you can appeal if you have a 'reasonable excuse'. HMRC accepts: serious illness, bereavement of a close relative, technical problems with HMRC's own systems, or unexpected events beyond your control. Appeal within 30 days of the penalty notice.
What is the minimum late filing penalty?
The minimum is £100 even if your tax bill is zero. Many people who file late with nothing owed still receive the £100 penalty.
Does late filing also mean late payment penalties?
Yes — late payment of tax carries separate penalties: 5% surcharge at 30 days, 5% at 6 months, 5% at 12 months — calculated on unpaid tax. Plus HMRC interest at base rate + 2.5% from 31 January onwards.
What if I filed my return but it was rejected?
A rejected return is treated as not filed. HMRC rejects returns for reasons like mismatched UTR numbers or invalid data. If HMRC's system rejected your return, you may be able to appeal the penalty. Always keep submission receipts.
How long does HMRC have to issue a penalty?
HMRC must issue late filing penalty notices within 4 years of the filing deadline. However, daily penalties can only go back to the notice that explains them — HMRC must formally notify you before daily penalties start.
What counts as a reasonable excuse for late filing?
HMRC publishes guidance on reasonable excuses: serious illness or hospitalisation, death of a close relative shortly before the deadline, computer failure if you could not have reasonably anticipated it, or HMRC's own service being unavailable.