Use form SA400 to register a new partnership for Self Assessment.
Use the SA400 if you need to register a new partnership for Self Assessment. The partner nominated by the partnership to receive and submit partnership returns must sign the form.
Complete the form online, print it, and post it to HM Revenue and Customs (HMRC).
If you’ve problems opening the online form you can use the PDF version of SA400. You’ll have to print this version and fill it in by hand.
Before you start
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You’ll need to fill in the form fully before you can print it. You can’t save a partly completed form so we suggest you gather all your information together before you begin to fill it in.