Paper vs online tax returns: why the 31 October deadline catches people out

Each year a number of people miss the paper tax return deadline without realising it was there. Most of us know that Self Assessment tax returns are due at the end of January, but that date only applies to returns filed online. If you send your tax return to HMRC on paper, the deadline is three months earlier, on 31 October.

Two deadlines for the same tax return

For the 2025 to 2026 tax year, which ran from 6 April 2025 to 5 April 2026, HMRC must receive most paper tax returns by 11:59pm on 31 October 2026. If you file your tax return online, you have until 11:59pm on 31 January 2027. Both ask for the same information. The difference is how the return reaches HMRC and how long you have to send it.

Why the 31 October deadline catches people out

The January date is the one most people hear about, so it is easy to assume it applies to everyone. Anyone who has always filed on paper, or who has asked HMRC for a paper form this year, can find the deadline has passed before they have started gathering their figures. It is also worth remembering that the deadline is about when HMRC receives your return, not when you post it. If you are sending a paper return close to the deadline, allow enough time for it to reach HMRC and keep evidence of posting, as this may be useful if there is a dispute about delivery.

What happens if you miss the paper deadline

A paper tax return that arrives on or after 1 November will usually result in a £100 late filing penalty. This applies even if you have no tax to pay or you pay your tax on time, although exceptions and appeals may apply in some circumstances. If you realise you will not make the paper deadline, HMRC's advice is to file online instead by 31 January, which means you can avoid the penalty. What you should not do is send a late paper return first, because the penalty may still be charged even if you then file online.

The benefits of filing online

As well as giving you an extra three months, filing online allows you to save your progress and return to the form later. If you are due a refund, submitting your return early may help you receive it sooner. You will need an HMRC online account to file this way, so it is sensible to allow time to set this up rather than leaving it until the last few days before the deadline.

Paying your tax bill

Whichever way you file, the deadline for paying any tax you owe for the 2025 to 2026 tax year is 31 January 2027. Sending a paper return earlier does not bring the payment date forward.

New to Self Assessment?

If you need to complete a tax return for 2025 to 2026 and have not filed one before, or you registered previously but did not need to file for 2024 to 2025, you needed to tell HMRC by 5 October 2026. If you register after that date, HMRC will give you a separate filing deadline, which will be three months from the date on the letter or email they send you. The normal payment deadline of 31 January 2027 still applies.

How we can help

If you would like help with your Self Assessment tax return, whether you file on paper or online, please get in touch with the team at Leathley and Co.