Register a partner for Self Assessment and Class 2 National Insurance
Register for Self Assessment and Class 2 National Insurance when you've joined a partnership using form SA401.
If you’re the nominated partner, you can register as a partner for Self Assessment and Class 2 National Insurance contributions using the online service. If you’re unable to use the online service, you can register by sending a postal form to HMRC.
Before you start
You’ll need:
- your National Insurance number
- your Unique Taxpayer Reference (UTR) if you have one
- the date your self employment started
- the date you joined the partnership
- the name, address and UTR of the partnership
- the Company Registration Number (CRN) if the partnership is a limited liability partnership (LLP) or limited partnership registered with Companies House on or after 25 October 2010
Only the nominated partner can register online. If you’re not the nominated partner and are joining a partnership, you must register by post.
Register online
You’ll need a Government Gateway user ID and password. If you do not have a user ID you can create one when you register.
Register by post
If you cannot register online, you can register by post.
You can either:
- fill in an online version of the form, then print it
- fill in the PDF version of the form on-screen, then print it
- print the PDF version of the form, then fill it in
You’ll then need to send your completed form to HMRC.
Complete an online version of the form
To use the online version of the form you need to:
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Get all of your information together before you start. You will fill this form in online and you cannot save your progress.
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Register using the online version of the ‘Registering a partner for Self Assessment and Class 2 NICs (SA401)’ form.
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Print and post it to HMRC, using the postal address shown on the form.
If the form does not open, contact online services support for more help.
This file may not be suitable if you use assistive technology (such as a screen reader). If you need a more accessible format, email different.format@hmrc.gov.uk and tell us what format you need. It will help if you tell us what assistive technology you use. Read the accessibility statement for HMRC forms.
Complete the PDF version of the form
You can either:
- print the form and fill it in
- complete the form on-screen, then print it
You’ll then need to post your completed form to HMRC, using the postal address shown on the form.
To complete the form on-screen you need to:
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Download and save the form on your computer.
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Open it using the latest free version of Adobe Reader.
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Complete it on-screen.
The form may not work if you try to open it in your internet browser. If the form does not open, contact online services support for more help.
After you’ve registered
We’ll usually contact you within 15 days of receiving your form but may take longer during busy periods.
If you registered online, you may be able to get your UTR sooner using the HMRC App or your personal tax account.
If we have not contacted you after 3 weeks, you can check when you can expect a reply.
Related forms and guidance
You can check what a paid agent can do on your behalf.
How you authorise the agent depends on the tax, and you may need to use paper form 64-8 or an online service.
Updates to this page
Published 23 April 2024Last updated 17 December 2024 + show all updates
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Information on what you'll need before you start has been added.
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Added translation