Important Calendar Dates for Businesses 2023/24

Please note that this article is intended for educational purposes only and should not be deemed to be or used as legal, tax, employment, or health & safety advice. For guidance or advice specific to your business, consult with a qualified professional.

When did the tax year start in 2023? And what date marks the end of the tax year 2023? In the United Kingdom, the tax year begins on the 6th of April of each calendar year and ends on the 5th of April of the subsequent year. So, in 2023, the tax year began on the 5th April and will end on the 6th April 2024. This means the answer to the question “What is the tax calendar year in the UK?” is 6th April to 5th April with the current calendar tax year being 2023/24.

As there are so many key tax deadlines and important business dates sprinkled throughout the calendar, it can be fairly easy to forget or overlook major events in the fiscal year. That’s why we’ve put together a handy guide to all the important dates when it comes to tax filing so that you can keep track and never miss a payment.

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Key tax dates for 2023 and the 2023/24 tax year

October 2023

5th October — Tell HMRC if you did not submit a tax return for the previous tax year but are required to submit one for this year.

31st October — If you are submitting your Self-Assessment tax return as a paper copy, it must be delivered to HMRC by this date.

December 2023

31st December — If you want HMRC to automatically deduct tax from your wages and pension, you must submit a Self-Assessment tax return by this date.

January 2024

31st January — Online Self Assessment tax returns are due. This is for freelancers, self-employed individuals or sole traders. The first instalment of payment is also due on the 31st of January. Missing this deadline without a very good reason usually results in a fine with penalties starting at £100 if your return is up to 3 months late.

February and March 2024

In anticipation of the new tax year commencing 6th April, companies should begin their end-of-year tax planning during these months.

April 2024

6th April — The 2024/25 tax year begins. Any adjustments to annual tax rates or threshold changes will come into effect on this day.

19th April - Complete and submit your Full Payment Summary and Employer payment summary for the previous year (ended 5 April 2023) and pay any tax/NIC due.

May 2024

31st May — Employees must be given a paper or electronic copy of their P60 form by this date. A P60 shows the tax that’s been paid on an employee’s salary in the previous tax year. They can use it to claim tax credits or as proof of income.

July 2024

5th July — PAYE Settlement Agreements must be paid by this date. This allows employers to make one annual payment to HMRC to settle all income tax and NIC due on minor employee expenses or benefits. It can help significantly reduce admin and boost compliance.

6th July — Deadline for submitting the expenses and benefits forms P11D and P11D(B) to HMRC. It is also the date by which Employment Related Security (ERS) Returns are required to be submitted.

19th July — This is the date by which HMRC must receive paper submissions of Class 1A National Insurance contributions. This is extended to 21st July for electronic copies.

31st July — The second payment on a self-assessment tax bill is due.


When did the tax year start in 2023?

The tax year started on the 6th of April 2023 and will end on the 5th of April 2024.

As Square integrates with Xero, Zohobooks and a number of other accounting software, you can automatically import your Square sales, refunds, invoice and transfers onto your accounting solution with Square Accounting.

What are the penalties for missing tax deadlines?

For Self-Assessment tax returns, filing late results in a £100 penalty if you’re late by up to 3 months. You’ll be charged even more if you take over 3 months to complete your return. Paying your tax bill late will also incur charges and you’ll have to pay interest on late payments.

Missing other important dates, such as the deadline for paying PAYE Settlement Agreements (5th July 2023), can result in you being fined or charged interest on late payments.

If you have a reasonable excuse, you may be able to avoid these fines and charges. Eligible excuses include the death of a loved one or a hospital stay.

Is 2023/24 a 53-week tax year?

2024 is a leap year, meaning week 53 at the end of the 2023/2024 tax year contains two days. This means employees paid on a weekly basis will receive 53 payments between the 5th April 2023 and the 6th April 2024. This final payment is referred to as ‘week 53’ and therefore makes 2023/24 a 53-week tax year.

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