Guides › Public Services › Late Self Assessment Tax Return: The Penalties
Late Self Assessment Tax Return: The Penalties
If your tax return is late you get an initial £100 penalty, even if you owe no tax. After 3 months you are charged £10 a day, up to £900. After 6 months there is a further 5% of the tax due or £300, whichever is more, and the same again after 12 months. Paying late adds 5% penalties at 30 days, 6 months and 12 months, plus interest. You can appeal if you had a reasonable excuse.
At A Glance
Your Rights
What the rules say, with a link to the official source for each.
How the Penalties Add Up
Late Filing
An initial £100 penalty. After 3 months, £10 for each day it is late, up to £900. After 6 months, a further 5% of the tax due or £300, whichever is greater. After 12 months, another 5% or £300, whichever is greater. source
Late Payment
You will be charged 5% of the unpaid tax at 30 days, 6 months and 12 months, and interest on the amount you owe. source
Appealing
If you had a reasonable excuse, you can appeal against a penalty, usually within 30 days of the penalty date. source
Time Limits to Know
Miss a deadline and you can lose a right. Check the dates on your own paperwork.
- 30 daysAppeal a penaltyFrom the date it was issued
- 3 monthsDaily penalties startAfter the deadline
Steps to Take
Step 1 of 5
File the return now: daily penalties keep building.
Step 2 of 5
Pay what you can, or set up a payment plan.
Step 3 of 5
Check whether you had a reasonable excuse.
Step 4 of 5
Appeal within 30 days using the form with the letter.
Step 5 of 5
Keep proof of what stopped you filing.
(Tap the numbers to reveal steps)
Where to Go If It Is Not Put Right
Your options, in order, and when each one applies.
HMRC
Contact HMRC through your personal tax account, the HMRC app or the phone and post details on GOV.UK.
Tax Tribunal
Independent. For appeals against tax decisions and penalties HMRC will not change.
Free Tax Help
TaxAid and Tax Help for Older People give free advice if your income is low.
Good to Know
Small things that make your complaint stronger.
Not getting a reminder from HMRC is not a reasonable excuse.
Scotland has its own Income Tax rates and bands. The rules on returns, penalties and HMRC complaints apply across the UK.
Want Help?
If you would like one of our team to look at your problem, our initial case review is free. We cannot guarantee any outcome and we do not give legal advice.
Lead reviewer
Luke Marley
Founder and Lead Reviewer
Luke founded CPUK in 2026 after seeing how hard it is for ordinary people to get problems with companies put right. He oversees our guides and checks them against official sources.
Research by Katie Burt, Co-founder and Operations Lead (17 years in the care sector, including managing services for vulnerable adults), and the CPUK Research Team. Researched with AI-assisted research tools, then checked and corrected by our team.
Last checked: 15 October 2026. We are not paid by the companies we write about. Adverts never affect our guidance. Read our editorial policy.
Sources and official links
- gov.uk/self-assessment-tax-returns/penalties Checked 15 October 2026
- gov.uk/tax-appeals/penalty Checked 15 October 2026