Calculator detail
UK Self Assessment late-filing calculator
Estimate the late-filing penalty stack for a Self Assessment return.
Category
penalties
Rule count
4
Calculator rules
- Immediate late-filing penalty = 100 GBP.
- After 3 months = 10 GBP per day for up to 90 days.
- After 6 months = greater of 5% of tax due or 300 GBP.
- After 12 months = another greater of 5% of tax due or 300 GBP.
Interactive calculator
This calculator applies the public HMRC late-filing penalty ladder for Self Assessment returns and keeps filing penalties separate from payment penalties.
Estimated late-filing penalty
£0.00
Important reminder
Late payment is separate
This estimate covers the filing-penalty stack only. HMRC can also charge late-payment penalties and interest.
Calculator caution
This calculator estimates filing penalties only. Late-payment penalties and interest may also apply.
Primary sources
- Self Assessment tax returns: penaltiesVerified 2026-05-01
Important disclaimer
This library is for general tax education only. Always verify filing obligations, due dates, and tax consequences against the cited primary source or with a qualified tax professional.