Self Assessment late filing penalties: the full breakdown for 2026

The penalty schedule

• 1 day late: £100 fixed penalty - applies even if there is no tax to pay or the tax is paid on time.
• 3 months late: £10 per day, up to a maximum of £900 (90 days).
• 6 months late: a further penalty of the greater of £300 or 5% of the tax due.
• 12 months late: another £300 or 5% of the tax due - more in serious cases where information is deliberately withheld.

Filed late but owe nothing?

You are still charged the £100 fixed penalty for a late return, and the daily penalties can still apply. Filing on time matters regardless of your tax position.

Can it be cancelled?

Yes - if you have a reasonable excuse and appeal within 30 days of the penalty notice. The £100 is the most commonly and successfully appealed penalty in the UK tax system.