Personal tax – form

Self Assessment: Register a partner for Self Assessment and Class 2 NICs (SA401)

Use the online forms service or the postal form to register for Self Assessment if you've joined a partnership.

Documents

Online form service

Print and post form (SA401)

Print and fill in by hand (PDF version)

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Detail

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 (you’ll need to log in to your tax account)
  • fill in form on-screen, print and post to HM Revenue and Customs

You should fill in the form fully before you print it as you can’t save a partly completed form so you should gather all your information together before you start to fill it in.

If you’ve 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.

Before you start

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Tax agents and advisers: authorising your agent (64-8)
Use form 64-8 to authorise HMRC to communicate with an accountant, tax agent or adviser acting on your behalf.