Started working for yourself?
Whether you call it freelancing, a side hustle or running your own business, there comes a point when HMRC needs to know about it.
If you earned money as a sole trader during the 2025/26 tax year, you may need to register for Self Assessment by 5 October 2026.
Here’s what you need to know.
Do I need to register for Self Assessment?
If your gross trading income was more than £1,000 between 6 April 2025 and 5 April 2026, you’ll normally need to register as a sole trader and complete a Self Assessment tax return.
Gross income means the money your business brought in before expenses are deducted.
So, if customers paid you £4,000 and you spent £1,500 on business expenses, it’s the £4,000 figure that matters when looking at the £1,000 threshold.
If your gross trading income was £1,000 or less, you may not need to register, although there are some circumstances where you might still want or need to.
When do I need to register?
For income earned during the 2025/26 tax year, you should tell HMRC that you need to complete a tax return by:
5 October 2026
This applies if you need to complete a return for the previous tax year and you’ve either never sent one before, or were previously registered but did not need to send one for 2024/25.
Started your business after 6 April 2026?
The October 2026 deadline isn’t for you yet.
If you started trading during the 2026/27 tax year, your first Self Assessment will relate to that later tax year.
How do I register as self-employed?
You register as a sole trader through HMRC’s Self Assessment service.
HMRC will ask a few questions about you and your circumstances and guide you through the appropriate registration process.
You’ll need your National Insurance number, so have that ready before you start.
What is a UTR?
Once you’re registered, you’ll have a Unique Taxpayer Reference, usually shortened to UTR.
It’s a 10-digit number HMRC uses to identify you for Self Assessment.
Keep it somewhere safe. You’ll need it when dealing with HMRC and your accountant.
What happens after I register?
Registering doesn’t mean you need to pay your tax immediately.
Your next job is making sure your income and allowable business expenses are recorded properly so that your tax return can be prepared.
For the 2025/26 tax year, the normal deadline for submitting an online Self Assessment tax return is:
31 January 2027
That’s also the normal deadline for paying the Self Assessment tax you owe.
What records should I be keeping?
Don’t wait until January to start looking for everything.
Keep records of your:
- business income
- invoices
- business expenses
- receipts
- bank transactions
- other information relevant to your business finances
Good records make completing your Self Assessment much easier — and help make sure you’re claiming the allowable expenses you’re entitled to.
What if I’ve missed the 5 October deadline?
Don’t ignore it.
If you should have registered and the deadline has passed, register as soon as possible. HMRC says you could receive a penalty if you tell them late.
The important thing is to get things moving rather than putting it off because you’re worried you’ve left it too late.
Registered? Let’s make the rest a Brease.
Self Assessment doesn’t need to become a January panic.
Brease keeps your sole trader accounts organised throughout the year, helps you understand what you can claim and takes care of your accounting deadlines.
And with Making Tax Digital for Income Tax changing how many sole traders report to HMRC, getting into good habits now can make the move to digital reporting much easier.
Less chasing paperwork. Less wondering what HMRC needs. More time to run your business.
Ready to get your accounts organised? Get your instant Brease quote and see your fixed monthly accounting fee.Or Ask Brease if you’re not sure what you need.
Looking for more simple business advice?
This guide is part of the Brease Guides collection, created to help sole traders understand bookkeeping, tax and Making Tax Digital without the jargon.
