Check if you need to register

You must register for Self Assessment if you earned more than £1,000 from self-employment in a single tax year (6 April to 5 April). This applies whether you:

• Work full time or part time for yourself

• Do freelance or contract work

• Run an online shop or sell goods/services regularly

Even if you’re employed and pay tax through PAYE, you’ll still need to register separately if you’re earning self-employed income on the side.

Register with HMRC

You need to register online through the GOV.UK website. Here’s how:

a) If you've never filed a Self Assessment before:

• Go to https://www.gov.uk/register-for-self-assessment

• Choose the option for registering as a sole trader

• HMRC will ask for your details and issue you a Unique Taxpayer Reference (UTR) by post (usually within 10 days)

• You’ll also receive an activation code for your online account

b) If you've filed a return in the past:

• You don’t need to re-register, but if you’ve stopped trading before and are starting again, you may need to reactivate your UTR

• You can do this by signing into your Government Gateway account and updating your self-employment status

At Go Cloud Accounting, we regularly help clients get registered with HMRC - and we can handle the whole process for you if you’d prefer not to deal with the admin yourself. 

When to register

You must register by 5 October following the end of the tax year in which you started trading.

For example; if you started trading in May 2025, which falls in the 2025/26 tax year, you must register by 5 October 2026.

It’s better to register as soon as possible - waiting too long risks delays in getting your UTR or access to file your return. It also gives you more time to get your bookkeeping in order and access tools like cloud accounting software. 

Key Self Assessment deadlines

Once you’re registered, here are the key dates you need to keep in mind:

• Register for Self Assessment by 5 October after the tax year ends

• File your tax return online by 31 January following the tax year

• Pay your tax by 31 January (first payment), 31 July (second payment on account, if due)

So, for income earned between 6 April 2024 and 5 April 2025, you must:

• File your return by 31 January 2026

• Pay any tax owed by the same date (plus a payment on account for the next year, if applicable)

What records to keep

From the start of your self-employment, you should keep clear records of:

• All income (invoices, sales records, bank statements)

• All business expenses (receipts, mileage logs, software costs, etc.)

You’ll need this information to complete your return - and HMRC can ask for proof, even years later.

At Go Cloud Accounting can help you get set up on cloud based accounting software like FreeAgent or QuickBooks which makes record-keeping simpler and keeps you prepared for your tax return. 

What happens after you file

After submitting your return:

• HMRC calculates how much tax and National Insurance you owe

• You’ll usually pay:

  • • Income tax (based on your profit)

    • Class 2 National Insurance (flat rate if you earn over the threshold)

    • Class 4 National Insurance (a percentage of your profit if over the threshold)

You may also have to make payments on account - advance payments towards the next year’s tax, based on your current bill.

Registering as a sole trader is simple, but doing it on time and keeping your records clean saves a lot of stress later on. If you’re unsure where to start, Go Cloud Accounting can register you, guide you through your first year, and take care of your tax return too.

This guide was written by Go Cloud Accounting - helping sole traders and small businesses across the UK stay compliant, organised and stress-free.

Ready to register for Self Assessment? Get in touch.