When Do I Need to Submit My Self Assessment Tax Return?

By Elizabeth Hughes

2 October 2026

Self Assessment

Tax FAQs

Paying Tax

4 mins

Table of contents

There’s always lots to do and plan when you’re running a business, but taking care of your tax return shouldn’t be near the end of the list. That’s right. We’re saying it. The Self Assessment deadline is never more than 12 months away, so getting your finance records ready will help. We’ll explain how to prepare for your tax return, and how soon you can submit your next tax return.

When is the Self Assessment tax return deadline?

The deadlines for filing Self Assessment and paying what you owe can be different depending on how you want to send your return and pay tax.

Action

Submit by post

Submit if you want to pay through your tax code

Submit online

Pay the bill

Deadline

5th October in your second tax year

31st October

30th December

31st January

For example

You earned money from renting out a property in the 2025/26 tax year (6th April 2025 – 5th April 2026).

The deadline for you to register for Self Assessment is 5th October 2026
To submit a paper return you’ll need to make sure HMRC receive your form by 31st October 2026
If you’re submitting online but want HMRC to collect the tax you owe through your wages or pension payments, the submission deadline is 30th December 2026
To submit online and pay the bill directly to HMRC, your deadline is 31st January 2027

We 100% recommend not waiting until the day to file. Anything can go wrong and thousands of other people are trying to do the same. The best time to file your Self Assessment tax return is before the New Year. It’s best to get it out of the way as soon as possible. Plus, if you’re due a tax rebate you’ll get it sooner!

The Self Assessment payment deadline

Hopefully you’ve been squirrelling money away from every payment so you have something set aside to pay your tax bill before the 31st January deadline.

Submitting your tax return early doesn't change the payment deadline.

Payments on account

If your Self Assessment tax bill comes to more than £1,000, then you’ll be required to make advance payments towards next year’s bill at the same time as paying this year’s bill.

Each advance payment is the equivalent to this year’s bill split equally in two:

The first payment is due 31st January - yep the same deadline for paying this year's bill. Surprise!
The second payment is due 31st July

Learn more about payments on account

What if I can’t pay on time?

If you’ve had to use it to replace your boiler or fix the weird noise on your car – don’t panic!

You might be able to talk to HMRC about arranging a Time to Pay agreement instead.

Preparing to complete your Self Assessment tax return

There’s no need to join everyone in the last minute scramble, so there are lots of things you can do to prepare your Self Assessment submission:

Get all your documents together: It’s a huge help when you have all your documents and accounting information in one place. Items can easily get missed if they’re all in different places.
Work out your expenses: If you want to reduce your tax bill (who doesn’t?) then spend time sorting out which allowable expenses relate to your business. If they're less than £1,000, you might be better off claiming for the Trading Allowance instead. Just remember that you can only claim the allowance or your expenses - not both. Choose the one which gives you the biggest reduction in your tax bill.

Learn more about preparing for Self Assessment

What happens if I miss the Self Assessment deadline?

The world won’t end but you will be out of pocket. Late tax returns incur an automatic £100 penalty. If you act quickly, you can reduce the fines but the penalties creep up the longer you leave it. These penalties are separate to the interest you’ll also be charged on any unpaid tax!

If you have a legitimate excuse for missing the Self Assessment deadline or not paying the full bill, get in touch with HMRC as soon as possible. They may approve your case so that you don’t have to pay penalties, and they will come to an agreement with you to help you pay what you owe.

Learn more about using Pandle to make business accounting easier. Create an account today and decide what to do with all the extra time you get back.

Elizabeth Hughes

A content writer specialising in business, finance, software, and beyond. I'm a wordsmith with a penchant for puns and making complex subjects accessible.

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