If you started working for yourself during the last tax year, there is an important date coming up.
5 October 2026.
This is the deadline for telling HMRC that you need to complete a Self Assessment tax return for the 2025/26 tax yearif you have not sent one before.
And importantly, registering for Self Assessment is not the same as submitting your tax return.
Here’s what you need to know.
Who needs to register?
You may need to register for Self Assessment if, during 6 April 2025 to 5 April 2026, you became responsible for reporting income to HMRC yourself.
For sole traders, one of the most common reasons is earning more than £1,000 from self-employment before expenses.
You may also need to complete a Self Assessment for other reasons, including receiving income from property, investments, dividends or overseas income.
If you are unsure whether you need to submit one, HMRC has an online checker you can use first.
What does registering actually do?
Registering tells HMRC that you need to complete a Self Assessment tax return.
Once registered, you’ll receive a Unique Taxpayer Reference, usually called your UTR.
This is a 10-digit number that identifies you for Self Assessment and is something your accountant will need if they are going to deal with HMRC and your tax return on your behalf.
Keep it somewhere safe.
How do I register?
You can register online through GOV.UK.
HMRC will ask a series of questions about your circumstances and direct you through the correct registration process.
If you are registering because you became a sole trader, you will normally need your National Insurance number and information about your self-employment.
If you don’t already have the necessary online sign-in details, you can create them as part of the process.
What happens next?
Once HMRC has processed your registration, you will receive your UTR.
You can then start preparing your first Self Assessment tax return.
For the 2025/26 tax year, the online filing deadline is 31 January 2027.
That is also normally the deadline for paying the tax you owe.
So registering by 5 October doesn’t mean you have to complete your return by 5 October. It means making sure HMRC knows you need to complete one.
Already registered before?
Don’t automatically register for a new account.
If you’ve previously been registered for Self Assessment but did not need to submit a return for 2024/25, you may need to reactivate your existing Self Assessment account instead.
HMRC’s registration service will help you work out what you need to do.
What if I miss 5 October?
Don’t ignore it.
Register as soon as possible.
HMRC says you could receive a penalty if you fail to tell them by the deadline when you are required to do so.
You will still need to deal with your Self Assessment and any tax due.
Your first Self Assessment doesn’t need to be complicated
Starting a business brings plenty of new responsibilities, and knowing what needs doing with HMRC isn’t always obvious.
That’s where we can help.
At North Devon Accounts, we can help you understand what you need to register for, get your records organised and prepare your first Self Assessment correctly.
Need help with your first tax return?
Book a free 30-minute consultation with our team in Braunton or Barnstaple and we’ll talk you through what happens next.
