Staying on top of key tax deadlines is essential for IT contractors and freelancers in the UK. Missing important dates can lead to penalties and complications with HMRC, so it's vital to keep your tax affairs in order. Whether you're filing your Self Assessment, making payments on account, or keeping track of VAT returns, knowing the correct dates will help you avoid unnecessary stress.
This guide highlights the most important UK tax dates for contractors and small businesses, ensuring you’re always prepared. From income tax deadlines to corporation tax and VAT obligations, we've outlined everything you need to know to stay compliant and manage your finances effectively.
We have put together a helpful guide on important UK tax dates you need to know and plan for the 2024/25 tax year.
| Date | Importance |
|---|---|
| 5th April 2025 | Last day of the 2024/25 tax year |
| 6th April 2025 | Start of the 2025/26 tax year |
| 31st July 2025 | Second payment on account for the 2024/25 tax year |
| 5th October 2025 | Deadline for Self Assessment registration for anyone who has become self-employed or has received additional income during the 2024/25 tax year |
| 31st October 2025 | Paper tax return submission deadline |
| 30th December 2025 | Online tax return submission if you have a tax bill and want the tax collected from your employment/pension* |
| 31st January 2026 | Online Self Assessment tax return deadline, payment deadline for 2024/25 tax bill and first payment on account for the 2025/26 tax year. |
| 5th April 2026 | Last day of the 2025/26 tax year |
5th April 2025 – Last day of the 2024/25 tax year
5th April 2025 is the last day of the 2024/25 tax year, by this date you should be thinking about getting all your paperwork and accounts in order. Getting your accounts organised at this time of the year will help you moving forwards, making your tax returns easier and available to submit to HMRC well in advance of the deadlines.
6th April 2025 – Start of the 2025/26 tax year
The first day of the new tax year for 2025/26 is when any new tax changes will come in to effect You should use the new tax year as an opportunity to see if you can improve the way you manage your accounts. Perhaps look at implementing new process for recording your income and expenditure – make the shift to digital record keeping if not already doing so.
31st July 2025 – Second payment on account for the 2024/25 tax year
Depending on how much tax you owe you may also be required to make two separate payments on account to HMRC, one in January and one in July. These are known as ‘Payments on Account’, which are advanced payments to cover you for the upcoming tax year. Both payments on account are 50% of the previous year’s tax bill, for example, if you paid £3,000 in tax for the 2024/25 tax year, you’d make one payment on account of £1,500 in January 2025, and another in July 2025.
5th October 2025 – Deadline for Self Assessment registration for anyone who has become self-employed or has received additional income
If you have recently become self-employed or have received additional income within the last tax year (2024/25) and you haven’t let HMRC aware of your change in employment status or income, you must notify them and register for self-assessment by 5th October 2025.
To complete this you’ll need:
Once you have registered for self assessment, you’ll receive a Unique Taxpayer Reference number (UTR) in the post within 10 working days or if you live abroad, it’ll take up to 21 days to receive this.
31st October 2025 – Paper tax return submission deadline
This is the deadline for paper tax returns. If you would rather submit your tax return online, you’ll have slightly longer to do so.
30th December 2025 – Online tax return submission
If you want HMRC to automatically collect the tax you owe from your wages and pension, you must submit your tax return by the 30th December but first, you’ll need to check if you’re eligible.
31st January 2026 – Online Self Assessment tax return deadline and first payment on account for the 2024/25 tax year.
This is the most important date of the whole tax year if you need to file a tax return.
You will have to submit your self assessment tax return by midnight on the 31st January. If you miss this deadline, you will incur an automatic £100 penalty.
As well as submitting your self assessment tax return, you’ll also have to pay tax due for the year on or before the 31 January. Plus, your first payment on account, the second payment on account will follow six months later (31st July).
5th April 2026 – Last day of the 2025/26 tax year
Finally, the 2025/26 tax year comes to an end and the next day you’ll be ready to start all over again!
Knowing and keeping an eye on the key tax dates is important when you have to file a self-assessment. When you know which dates to be prepared for, you’ll have more time to focus on your business rather than worrying about tax.
With the help of a tax software, you simply input your data and it does the calculations. This is done in real time, so you can get a clear picture of your finances no matter how far away the Self Assessment deadline may be.
Contributions By: CCM | Carter Collins & Myer Accountants