31 October Paper Tax Return Deadline: Should You Use It?

The paper Self Assessment deadline for the 2025/26 tax year is 31 October 2026. If you file online instead, you have until 31 January 2027 — but a paper return that arrives after 31 October is late, even though the online deadline has not yet passed.

That catches out a small but steady number of people every autumn: they post a paper return in November, assuming January is the deadline for everyone, and receive a penalty. This guide explains who the 31 October date matters to, how paper and online filing compare, and what to do with five weeks to go.

Key takeaways

• Paper returns for 2025/26 must reach HMRC by 31 October 2026.
• Online returns for the same year are due by 31 January 2027.
• Payment is due by 31 January 2027 whichever way you file.
• If you miss 31 October, switch to online filing rather than posting late.
• Filing early can let HMRC collect smaller amounts through your tax code, if you qualify.

What the paper deadline is

A Self Assessment tax return can be filed in two ways: online through HMRC's service or compatible software, or on the paper SA100 form. Each has its own deadline. For a tax year ending on 5 April, a paper return is due by the following 31 October, and an online return by the following 31 January. The dates are set out on GOV.UK's Self Assessment deadlines page.

The deadline is about when HMRC receives the return, not when you post it. Leave time for the post, particularly in the last week of October.

Paper and online filing compared

Who still files on paper

Most people now file online, but paper is still used by people who are not comfortable with online services, who have not yet set up an HMRC online account, or whose circumstances are not supported by the online service. If you prefer paper, download the current SA100 tax return from GOV.UK along with any supplementary pages you need, such as those for self-employment or property income.

If you are newly self-employed and have not yet registered, registration was due by 5 October 2026 for the 2025/26 year. Our guide to the Self Assessment registration deadline explains what to do if you missed it.

Filing early to pay through your tax code

If you are employed or receive a pension and owe less than a set limit, HMRC may be able to collect the tax through your tax code over the following tax year, instead of asking for a single payment. To be considered, the return must be filed on paper by 31 October or online by 30 December. Check the current limit and conditions on GOV.UK. For some people, this alone is a good reason to file early.

Step by step: with five weeks to go

1. Decide now whether you are filing on paper or online.
2. If online, check you can sign in to your HMRC account today, not in January.
3. Gather P60s, P11Ds, bank interest, dividend and pension figures for 2025/26.
4. If self-employed, total your income and allowable expenses for 6 April 2025 to 5 April 2026.
5. If filing on paper, complete the SA100 and supplementary pages and keep a copy.
6. Post it with proof of postage in good time to arrive before 31 October 2026.
7. Diarise 31 January 2027 for payment, whatever method you used.

Worked example (illustrative example)

"Graham", an invented illustrative example, is employed and also earns a modest amount from weekend photography. He has always filed on paper, usually in January.

Last year his paper return arrived in HMRC's post room in mid-November. It was late, because the online deadline did not apply to a paper return, and a late filing penalty followed. This year he has two better options. He can post his paper return by early October so it arrives before 31 October 2026. Or he can set up his HMRC online account now and file online any time before 31 January 2027.

Because the tax he owes is small and he is employed, filing by 31 October on paper, or by 30 December online, may also let HMRC collect it through his tax code. Graham and his figures are invented to show how the dates interact.

Common mistakes

• Assuming 31 January applies to paper returns. It does not; the paper deadline is 31 October.
• Posting on the last day. The return must be received, not just sent, by the deadline.
• Leaving online account setup until January. Access can take time to arrange.
• Thinking early filing means early payment. Payment is still due by 31 January.
• Forgetting supplementary pages. Self-employment and property income need their own pages with the SA100.

Getting it handled

Our personal tax service starts from £180 per year and files your return online, so the 31 October paper deadline no longer matters. If you are already behind on earlier years, start with our Self Assessment catch-up plan.

Short on time before 31 October? Get in touch or see our pricing.