23 September 2026
Do you need to register for Self Assessment?
If you received untaxed income during the 2025/26 tax year, you may need to complete a Self Assessment tax return.<br /> <br /> If this is your first time completing one, there is an important date to remember… 5th October 2026.<br />
What is the 5th October deadline?
If you meet the Self Assessment criteria for the 2025/26 tax year and are not already registered with HMRC, you need to register by 5th October 2026.
The 2025/26 tax year covers income received between 6th April 2025 and 5th April 2026.
Who needs to register?
There are several reasons why you may need to register for Self Assessment. For example, if you:
- Became self-employed and had gross trading income of more than £1,000
- Became a partner in a business partnership
- Started receiving income from property or land
- Need to pay the High Income Child Benefit Charge and are not paying it through PAYE
- Sold or disposed of an asset and need to pay Capital Gains Tax
Once registered, HMRC will provide you with a 10-digit Unique Taxpayer Reference (UTR), which you will need for your tax return.
How do I register?
You can register for Self Assessment directly through the HMRC website.
Alternatively, Stratos can take care of the registration process and deal with HMRC on your behalf, giving you one less thing to worry about.
What if I miss the deadline?
If you miss the 5th October deadline, don’t ignore it. Register with HMRC as soon as possible.
A failure to notify penalty may apply depending on your circumstances, including whether there is tax still unpaid after the payment deadline.
I registered years ago – do I need to register again?
If you have previously been registered for Self Assessment but HMRC no longer requires you to submit a return, you may need to reactivate your Self Assessment account rather than register from scratch.
Need some help?
If you are unsure whether you need to register, or would like help completing your Self Assessment tax return before the 31 January 2027 deadline, please speak to a member of our team.
Let Stratos help you navigate the way.
Speak to our team for advice based on your circumstances. We are here, navigating the way through the rules and towards the right next step.
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