HMRC Self Assessment Penalties (for Late Filing and Payment)

HMRC applies penalties automatically if deadlines are missed.

Late Filing Penalties

• £100 – Immediate penalty after the deadline, even if no tax is owed.
• 3 months late: £10/day, up to £900.
• 6 months late: £300 or 5% of tax due (whichever is higher).
• 12 months late: Additional £300 or 5% of tax due (whichever is higher).

Example: If your tax due is £1,000 and your return is 7 months late, HMRC can charge £300 + £50 (5% of tax due) plus daily penalties.

Late Payment Penalties

• Interest begins accruing from 1 February 2026 on any unpaid tax.
• 5% at 30 days late.
• 5% additional at 6 months late.
• 5% additional at 12 months late.
  Interest continues until the full amount is paid.