Posted September 21, 2023

Tax Deadlines for 2023/24 – Key Dates for Self-Assessment Tax Returns

6th April – Start of the Tax Year

The tax year runs from 6th April to 5th April the following year, any income earned in this period needs to be reported on your self-assessment tax return.

This is also the date any new tax rates or allowances announced in the budget are implemented.

Fun Fact: The tax year begins on 6th April because, until 1752 the tax year started on 25 March (the old New Year’s Day) but there was a difference of 11 days between the Julian calendar that Britain used and the Gregorian calendar that Europe due to the leap years. To align with Europe, Britain moved to the Gregorian calendar and lost the 11 days. To ensure that there was no loss of tax revenue, the tax year remained at 365 days ending on 4th April. In 1800 the start of the tax year moved a further day to 6th April, again due to a leap year in the Julian calendar and not the Gregorian calendar and it has remained on 6th April ever since.

31st July – Second Payment on Account Due

If you need to make a payment on account (check out our handy blog on POA here), the second payment on account is due by midnight on 31st July. If you think your tax might be lower than last year, it is worth submitting it before this date so you can amend your payment.

5th October – Registration Deadline

If the first year you need to submit a tax return for has just past, this is the deadline you need to register by. So for tax year 2023/24, you need to register by 5th October 2024. Failure to register on time can result in a penalty.

31st October – Deadline for Paper Tax Returns

If you like to file a paper return the deadline for submission is 31st October.

Fun fact – less than 5% of tax returns are filed as paper returns.

30th December – Opt to Pay via PAYE

If you also pay tax via PAYE, you have the option to pay any overdue tax over 12 months via your tax code. To qualify, you must file your tax online before 30th December, and your tax bill must be less than £3,000.

31st January – Deadline for Filing Online Tax Returns AND Payment Deadline

This is the most important date for self-assessment returns. If you are filing your return online, it must be submitted by midnight on 31st January. HMRC’s website is very busy on 31st January and it can sometimes take a while to submit.

You also need to pay any tax that you owe by this date as well as your first payment on account for the next tax year.

Fun fact – 861,085 tax returns were filed on 31st January 2023 with 36,767 of them being filed in the hour before the deadline!

5th April – End of the Tax Year

This is the end of the tax year.


If you still need help with your tax return, you can give us a call on 0113 258 2437 or email the team here