SA400: Registering a partnership for Self Assessment
Form SA400 registers a new partnership for Self Assessment with HMRC so the partnership gets its own Unique Taxpayer Reference and can file a partnership tax return.
This is the genuine HMRC PDF, unmodified. Source: HMRC official page.
What is SA400?
A partnership is a separate entity for Self Assessment. As well as each partner registering individually, the partnership itself has to be registered and file its own return showing the profits and how they are shared. SA400 is the paper route to do that, completed by the nominated partner who takes responsibility for the partnership's tax affairs.
The two page form asks for the partnership name and trading address, the nature of the business, the date trading started, the accounting date, and the nominated partner's details. There is also a box for the number of form 64-8 authorisations enclosed if an agent is being appointed for the partnership or its partners at the same time.
Who files SA400?
- The nominated partner registering a newly formed partnership
- Partnerships that need a UTR before their first partnership tax return
- Partnerships taking on a tax agent who are enclosing form 64-8
- Partnerships that cannot use the online registration service
How to fill out SA400
- Agree which partner will be the nominated partner responsible for the partnership return.
- Enter the partnership name, trading address, business description and the date the partnership started trading.
- Give the accounting date the partnership will use and its contact details.
- Enter the nominated partner's name, address and National Insurance number, and note how many 64-8 forms you are enclosing.
- Sign and post the form to HM Revenue and Customs, National Insurance Contributions and Employer Office, BX9 1AN.
Quick fill SA400 on this page
Prefer to see the form itself while you type? Open SA400 in the editor to fill it on the actual pages, add a signature, and download.
Frequently asked questions
Does registering the partnership register the partners too?
No. Each partner must also be registered individually for Self Assessment and Class 2 National Insurance, normally using form SA401 for individuals or SA402 where the partner is not an individual.
Can I register online instead?
Yes. The nominated partner can register the partnership through HMRC's online service with a Government Gateway user ID. The paper SA400 exists for those who cannot or prefer not to use it.
How long does registration take?
HMRC aims to reply within about 15 days of receiving the form, though it can take longer at busy times such as the run up to the filing deadline.