Personal tax – form

Self Assessment: register a partnership for Self Assessment (SA400)

Use the online forms service or the postal forms to register a new partnership for Self Assessment.


Online form service

Print and post form (SA400)

Print and fill in by hand (PDF version)

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Use the SA400 to register a new partnership for Self Assessment. The partner nominated by the partnership to receive and submit partnership returns must sign the form.

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

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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64-8: Authorising your agent