If you are self-employed or run your own business in the United Kingdom (UK), then it is a must for you to remember the deadline for the self-assessment tax return. It is a vital date that helps you pay the tax promptly before encountering a heavy fine.
Moreover, you might be well aware that no matter if you are a solo businessman, business partner, or even a firm director, you must make sure to file a tax return to HMRC each year.
So, if you are among those taxpayers who have not yet filed their online self-assessment tax return or paid the tax due. In that case, we at Msaziz & Co recommend you act fast before you miss the deadlines and, unfortunately, face fines of around £100 – plus 7.25% interest on late tax payments.
When is the Self Assessment Deadline?
If you are looking for a self-assessment tax return deadline, we are glad to update you that January 31, 2025, is the deadline. However, you might have a different deadline if you get an online tax return from HRMC after October 31, 2024. In such cases, you still have 3 months from the issue date to file.
Additionally, if you’re self-employed, then January 31 is the date you must make your 1st payment for the 2024-25 tax year, along with a balance payment if any tax is due from 2023-24 income. However, if you unfortunately make your payment late, you must bear interest from HMRC. Furthermore, interest on payments is calculated at 2.5% plus the Bank of England base rate.
April 6, 2025: First Day of the New 2025-26 Tax Year
It is worth mentioning that the new tax prices and allowances for 2025-26 will take effect by April 6. Therefore, be well aware of the changes if they occur. So, in case you’ve all the data, then you better file your 2024-25 tax return from this date.
July 31, 2025: Second Payment on Account Due
Self-employed people who pay taxes on account must make sure to make their 2nd payment by July 31 at midnight. Moreover, the payment you pay is a projection based on your 2023-2024 income. However, in case you still owe taxes even after paying the payment, you must make another balancing payment on January 31, 2026.
October 5, 2025: Register for Self-Assessment
If you are among those who have not yet submitted a self-assessment tax return before, the good news is that you can register by October 5, 2025, to submit a return for the 2024-25 tax year. The good thing is that it lets you obtain your activation code along with the Unique Taxpayer Reference (UTR) number, which you will need to file your first return.
October 31, 2025: Paper Tax Returns Due
As mentioned, October 31, 2025, is the last date for filing a paper tax return. Moreover, if you got a notification from HMRC stating that you are required to file a tax return after July 31, 2025, then understand that you have 3 months from the date of the notice to return the completed form.
In addition, we recommend you don’t be tempted to try to file your tax return after the due date. Instead, as they are not due until January 31, then you still have the opportunity to pay online tax returns. But remember to don’t submit both of them.
December 30, 2025: Opt into PAYE
In case you file your tax return online and have wages taxed under PAYE, you can collect overdue tax through your tax code for the following year. However, in order to be eligible, you must make sure that your tax bill is less than £3,000.
Remember, you are also required to submit your online return by December 30, 2025. In addition, the benefit is that any taxes due would be paid over 12 months starting from April 2026 instead of a single lump sum by January 2026.
Fines for Late Tax Returns
There is no doubt that fines must be paid in case someone misses the deadline to pay the tax. Unfortunately, they have to bear extra penalty fines and interest charges. However, if you are wondering about the fines for late tax returns, then check out below:
One Day Late
The late taxpayer must pay a £100 fine for filing even just a day after the deadline.
3 Months Late
If you have missed the deadline, then after 3 months, you will be penalized £10 for every extra day after the 3 months (up to a maximum of 90 days), in addition to the £100 initial or original fine, for a total of £1,000.
6 Months Late
After 6 months, you will be fined either £300 or 5% of the tax due (whichever is greater), in addition to the prior mentioned penalties.
12 Months Late
After 12 months, you will face an additional £300 fine, or 5% of the tax due, along with the above penalties. Furthermore, you could also be fined 100% of the tax due in the most critical situations. Despite that, there will be more penalties if you pay your taxes late.
How to Submit Your Tax Return? (2 Easy Steps)
It is pertinent to mention that if you have never submitted a tax return, you must be sure to register with HMRC. Once you are done, select two ways to submit your tax return:
- Fill out the paper tax return and then post it to HMRC
- You can also submit it online by visiting the HMRC’s official website
Conclusion
This was all about the tax returns 2025: important deadlines. Being self-employed or a person who runs their own business in the United Kingdom (UK), you must remember the deadline for the self-assessment tax return, which is January 31, 2025.
So, we at Msaziz & Co recommend you act fast as this date is crucial for you to remember, as it will help you pay the tax on time before it gets too late and you come across a huge fine. You can also get in touch with us if you are looking for tax obligations, as our aim is to ensure you’re well-informed and abide by the latest accounting and tax obligations set by authorities like HMRC.