October Deadlines: Why the 31st October Self Assessment Cut-off Matters (and Why Online Filing is Better)

Every year, October sneaks up faster than we expect. For many people, it means crisp mornings, pumpkins on doorsteps, and maybe even a little Halloween fun. But for thousands of self-employed people and landlords, October also brings something less exciting: the paper Self Assessment deadline.

If you want to file your tax return on paper, 31st October is the cut-off. Miss it, and you’ll face an automatic £100 fine.

But here’s the thing: in today’s digital world, paper returns are rarely the best option. Filing online gives you until 31st January 2026, extra flexibility, and a lot less stress. In this blog, I’ll explain why the October deadline matters, why online filing is smarter, and how you can avoid last-minute panic.

Why 31 October matters

HMRC gives you two options for filing your Self Assessment tax return:

• Paper filing - deadline 31st October 2025

• Online filing - deadline 31st January 2026

If you’re still filing on paper, your tax return for the 2024/25 tax year must reach HMRC by the end of October. Even if you post it on the 31st, delays could mean it doesn’t arrive in time. And yes - HMRC will still fine you if it’s late.

Why paper returns are fading out

HMRC has been encouraging people to move online for years. In fact, more than 95% of taxpayers already file online. Paper forms are harder to process, more likely to contain errors, and can easily get lost in the post.

For most people, there’s no real advantage in sticking to paper. Unless you have very specific reasons (for example, accessibility needs), online is the way forward.

The benefits of filing online

1. Extra time

   Instead of rushing to meet the October deadline, you have until 31 January 2026. That’s three whole months of breathing space.

2. Instant confirmation

   When you submit online, HMRC confirms straight away that they’ve received your return. No worrying if the post arrived on time.

3. Fewer errors

   The online system checks for common mistakes, helping you avoid penalties or under/overpayments.

4. More flexible payment options

   Once you file online, you’ll see your tax calculation immediately and can set up a payment plan if you need to spread the cost.

Why leaving it late still causes problems

Even with the online deadline in January, leaving it until the last minute is never a good idea. The longer you wait:

• The harder it is to pull together all the information.

• The busier accountants (like us!) become, which means less availability for support.

• The more stressful it feels, especially over Christmas and New Year.

October is actually the perfect month to get your return filed online. You avoid the January rush, you can plan for your tax bill early, and you’ll have one less thing on your mind as the year winds down.

How Barleyfields can help

At Barleyfields, we’ve seen every kind of tax return: the neat, the messy, and the ones rescued from shoeboxes full of receipts!

We can:

• Move you from paper to online filing with zero stress.

• Keep your records tidy so future returns are a breeze.

• File early, so you know exactly what you owe and when.

Our aim is to make sure Self Assessment doesn’t haunt you this autumn 👻.

My final thoughts

The 31st October paper deadline is a useful reminder: it’s time to think about your Self Assessment. But rather than scrambling for the post, take the smarter route. File online, give yourself until January, and make life easier.

And if you’d rather not worry about it at all? That’s what we’re here for.

Get in touch with Barleyfields today and let’s get your tax return sorted before it becomes a nightmare.

Emma

Barleyfields Accountancy