Self Employment Tax Guide​

Self Assessment – Registering as Self Employed

You’ll need to register for Self Assessment as soon as you can after starting your business. You need to do this even if you’ve completed tax returns before.

You need to register by 5th October in your business’s second tax year. You could be fined if you don’t.

If you’ve sent a return before

Register online using Form CWF1.

You’ll need to find your 10-digit Unique Taxpayer Reference (UTR) from when you registered for Self Assessment previously.

If you’ve signed up for the online service before, you should use the same account to file your tax return.

If you haven’t sent a return before

Register online via your Tax Account and you’ll:

• get a letter with your 10-digit Unique Taxpayer Reference (UTR)
• be enrolled for the Self Assessment online service at the same time

You’ll also get a letter within 10 working days (21 days if you’re abroad) with an activation code.

You’ll need this when you first log in to your online account. You can replace an activation code if you don’t receive it or you lose it.