Registering as
self-employed.

When do you actually have to register?

The deadline is 5 October following the end of the tax year you started trading in. Start in June 2026 and the tax year ends 5 April 2027, so you must register by 5 October 2027.

That is the legal deadline, not the sensible one. Registering when you start means your records begin on day one instead of being reconstructed a year later, and it costs nothing to be early.

If your self-employed income is under the trading allowance of £1,000 in a tax year, you may not need to register at all — though you can choose to, which is sometimes worth doing to record a loss.

How do you register?

1. 1

   Create a Government Gateway account

   If you have ever filed a return or claimed anything from HMRC online, you may already have one. Use the existing account rather than creating a second.

2. 2

   Register for Self Assessment as self-employed

   You will be asked what you do, when you started, and your contact details. The date you started trading matters — it sets which tax year your first return covers.

3. 3

   Wait for your UTR

   The Unique Taxpayer Reference arrives by post, usually within a couple of weeks. It is yours permanently, across every business you ever run.

4. 4

   Activate the service

   A separate activation code arrives, also by post. Both letters are needed, and both go to the address HMRC holds for you, so make sure that is current first.

What happens after you are registered?

• —You file a Self Assessment return each year covering 6 April to 5 April.
• —The online filing deadline is 31 January after the tax year ends; paper is 31 October.
• —Payment is due 31 January, and payments on account may fall due in January and July.
• —You pay National Insurance through Self Assessment alongside income tax.
• —You keep records for at least five years after the 31 January deadline they relate to.

What do people get wrong?

The most common mistake is treating registration as the end of the admin rather than the start of it. The return is easy if the records exist and miserable if they do not.

The second is not putting tax aside. Nothing deducts it for you, and the first January bill can include a payment on account for the year ahead — which catches almost everyone once.