Register for and file your Self Assessment tax return

Register if you're self-employed

If you have to send a tax return and did not send one last year, you need to register for Self Assessment and Class 2 National Insurance.

Register by 5 October in your business’s second tax year. You could be fined if you do not.

If you’ve sent a return before

Register online (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 have not sent a return before

Register online 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 do not receive it or you lose it.

Other ways to register

You can fill this form on-screen then print off and post to HMRC. You’ll need to have all your information ready as you cannot save a partly completed form.

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