SA401: Registering a partner for Self Assessment and Class 2 NICs
Form SA401 registers an individual partner for Self Assessment and Class 2 National Insurance contributions when they join a partnership.
This is the genuine HMRC PDF, unmodified. Source: HMRC official page.
What is SA401?
Registering the partnership on SA400 is only half the job. Every individual partner also has to be registered in their own right so that HMRC can issue a Unique Taxpayer Reference, set up their Self Assessment record and deal with Class 2 National Insurance on their share of the profits. SA401 is that individual registration.
The form collects the partner's name, address, date of birth and National Insurance number, the partnership name and UTR, the date they joined the partnership, and details of any previous self employment or Self Assessment record. It also covers the National Insurance questions HMRC needs to decide the Class 2 position.
Who files SA401?
- Individuals joining an existing partnership or forming a new one
- Partners who are not the nominated partner and so must register by post
- Partners who need a UTR before filing their first personal tax return
- Existing self employed people moving into a partnership
How to fill out SA401
- Have the partnership name and its UTR ready, along with your own National Insurance number.
- Enter your personal details, including any previous names and addresses HMRC would hold you under.
- Give the date you joined the partnership and details of any earlier self employment or Self Assessment record.
- Answer the National Insurance questions so HMRC can set up your Class 2 contributions correctly.
- Sign the declaration and post the form to HM Revenue and Customs, National Insurance Contributions and Employer Office, BX9 1AN.
Quick fill SA401 on this page
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Frequently asked questions
What is the deadline for registering?
HMRC's Self Assessment registration deadline is 5 October following the end of the tax year you need to file for, so register by that date for the year you became a partner. Check the exact date for your year on gov.uk.
Can I register online?
The nominated partner can register online, but other partners generally register by post using SA401. Check the current guidance on gov.uk for which route applies to you.
What if the partner is a company or a trust?
SA401 is for individuals. Where the partner is a company, trust or other entity, HMRC uses form SA402 instead.