You fill in a CWF1 form to tell HMRC that you are self-employed and need to do a Self Assessment. You can use it both to register or to re-register as a sole trader.

After you’ve submitted your CWF1 form, you’ll be given a Unique Taxpayer Reference (UTR) number, which you use to pay your tax return.

What’s a CWF1 form?

You’ll have to fill in details about your:

• Name
• Address
• Business address
• National Insurance number
• Business details

Click here to fill in your CWF1 form with HMRC.