The HMRC deadline for paper submissions is 11:59 pm on 31 October. Most people file online these days, but more than 300,000 taxpayers still use the paper route.
If you miss the 31st of October deadline
You do not automatically incur a £100 late filing penalty for missing the paper deadline if you file online by 11:59pm on 31 January 2026.
The penalty is triggered by the first return you actually submit.
If your first submission is a late paper return sent after 31 October, the £100 penalty applies.
If your first submission is an online return by 31 January, no late filing penalty is charged.
- Official guidance on dates is here: GOV.UK Self Assessment deadlines.
- An independent explanation of how the “first return received” rule works is here: LITRG: tax return deadlines.
Who can still file a paper tax return?
In theory, anyone can still file a paper return if they request a form in advance and meet the 31 October deadline.
In practice, HMRC expects most people to file online and reserves paper for specific situations. HMRC no longer automatically sends paper forms to most taxpayers.
You usually need to request one and explain if you have a genuine reason not to file online, such as a disability, lack of internet access, or religious grounds.
- Requesting a paper return: Request a paper tax return
- General Self Assessment forms and help: GOV.UK Self Assessment
If you prefer to submit a paper return and can post it in time, HMRC will still process it.
If you are close to the cut-off, consider switching to online to avoid delays in the post. Blank SA100 forms are not provided as downloadable PDFs.
Penalties if you file late
If your tax return is submitted ‘late’ using any method, the penalties can quickly accumulate.
These penalties apply even if there is no tax to pay.
- Initial automatic fine, £100
- After 3 months, £10 per day, up to £900
- After 6 months, 5% of the tax due or £300, whichever is higher
- After 12 months, a further 5% or £300, whichever is higher
For more details, read this article: GOV.UK penalties for late Self Assessment tax returns.
Something many people don’t consider when filing late is that it increases the risk of an HMRC investigation.
You also run the risk of being investigated by HMRC, which can be an incredibly stressful and expensive ordeal. Failing to complete your tax return or even completing it but late is one of the red flags to HMRC, which in recent years has taken a tough approach to those it suspects of non-compliance. — Seb Maley, CEO at Qdos
See our guide to tax investigation insurance for more details.
Paper vs online tips
If you want to file a paper tax return, send it well before the deadline and consider using registered or signed-for post.
Postal delays—which seem to be more frequent than ever—cannot be used as a reasonable excuse.
If time is tight, consider switching to the online service, which is used by the vast majority of people.
You have until 31 January 2026 to file online, and the same date applies to pay any taxes you owe. Start here: Register and sign in to HMRC online services.
Some more useful reading
- How to complete your Self Assessment tax return on ByteStart
- 5 October registration deadline explained on ByteStart
- GOV.UK Self Assessment deadlines
Remember The deadline to pay your Self Assessment bill is 31 January 2026, whether you filed on paper or online. If you file early, you will avoid penalties, long phone queues, and January stress!
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