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Use the SA401 to register as a partner for Self Assessment and Class 2 National Insurance contributions.
To register you can:
use the online service
fill in form on-screen, print and post to HMRC
To use the online service, you need a Government Gateway user ID and password. If you do not have a user ID you can create one when you use the service.
You should fill in the form fully before you print it as you cannot save a partly completed form so you should gather all your information together before you start to fill it in.
If you have problems opening the online forms you can use the PDF version. You’ll have to print this and fill it in by hand before posting it to HMRC.
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