What is a CWF1?
The CWF1 is a form which you need to fill out to let HMRC know that you are self employed. You must only use the CWF1 form if you are already registered for self assessment, for example you are a landlord but have now decided to work for yourself and need to declare self employment income.
You Can Find the CWF1 Online
You can complete this form online here and you’ll need to find your 10-digit Unique Taxpayer Reference (UTR) from when you registered for Self Assessment previously as well as providing details about your self employment.
Why Do You Need to Complete A CWF1?
The CWF1 is a way of formally notifying HMRC that you have self employment income which you need to declare to them as part of your self assessment tax return and (depending on your earnings) pay tax and national insurance to them on.