The 31 October Paper Tax Return Deadline: What It Actually Means For You

Mike Jackson FCCA

Oct 12

3 min read

Updated: Oct 24

Most people filing a Self Assessment tax return now do it online, with the familiar 31 January deadline fixed firmly in the diary. But if you're one of the smaller number of taxpayers still submitting a paper return, the clock runs out a lot sooner. Paper returns for the 2025/26 tax year are due by 11:59pm on 31 October 2026 — a full three months ahead of the online cut-off.

Who does the paper deadline actually apply to?

HMRC no longer automatically posts out paper SA100 forms to most people, and it actively encourages online filing. In practice, paper returns are mainly used by:

People who are digitally excluded — no reliable internet access, or unable to use HMRC's online services
People who object to online filing on religious grounds
Anyone HMRC has agreed, in advance, can file on paper for another accepted reason
A small number of people who simply prefer paper and have requested a blank SA100 form from HMRC in advance

If none of those apply to you, filing online is almost certainly the better route — and it's the one most of our clients at Jackson Lee Accountants in Bury already use.

What happens if you miss 31 October?

Missing the paper deadline doesn't automatically mean the standard £100 late filing penalty applies — what matters is which return HMRC receives first. If you miss 31 October but then file online before 31 January 2027, that online return is treated as your return, and no penalty applies for lateness. It's a genuinely late paper return — submitted after 31 October with nothing filed online in its place — that triggers the penalty regime:

£100 automatic penalty, even if you owe no tax or are due a refund
£10 per day after 3 months, up to a maximum of £900
A further 5% of the tax due, or £300, whichever is higher, at 6 months
Another 5% of the tax due, or £300, whichever is higher, at 12 months

The payment deadline doesn't move

Whichever method you use, the balance of tax you owe for 2025/26 is still due by 31 January 2027, along with your first payment on account for 2026/27 if you're within that regime. Filing on paper in October doesn't bring payment forward, and filing late doesn't push it back — HMRC charges interest on anything paid late regardless of how or when the return itself was submitted.

If you're filing on paper this year

A few practical points worth bearing in mind:

Postal delays aren't accepted as a reasonable excuse for a late return, so allow plenty of time and consider sending by tracked or signed-for post
Blank SA100 forms aren't available as a simple download — you normally need to request one from HMRC in advance
If your circumstances have changed and you can now file online, it's often worth switching rather than cutting it fine with the post

Getting it right, either way

Whether you're filing on paper or online, the bigger risk with Self Assessment is rarely the format — it's leaving the figures until the last minute, especially with the Autumn Budget landing on 28 October and potentially changing the picture for next year's return. If you'd like help getting your 2025/26 return finished and filed correctly, whichever way you submit it, Jackson Lee Accountants in Bury is happy to take it off your hands.

Need a hand with this? We're accountants in Bury, and our self assessment tax return service covers it for a fixed fee.