What is SA401?

SA401 is a form issued by HMRC specifically for an individual partner of a business registered as a Partnership. HMRC uses the form to register a partner for self assessment and class 2 national insurance contributions.

The SA401 should only be completed by an individual, with a partner who is not an individual needing to complete a different tax form called SA402.

Examples of a partner that is not an individual is a trust, company or another partnership.

The partnership itself will submit a form SA400 to register for self assessment.

How do I complete SA401?

SA401 to register a partner can be submitted online using HMRC’s online service or you can complete the form on screen and then print and post it to HMRC.

You will need to be registered to use the government gateway to be able to submit the SA401 online.

The SA401 is broken into three parts with part one about the partner, part two about the partnership and part three a declaration.

To complete the SA401 you will need:

• Your national insurance number.
• Your UTR number.
• Partnership name and address.
• Partnership UTR number.

SA401 unique tax reference number

Following the submission of your SA401 you will be sent by HMRC a UTR number which is made up of ten numbers. The UTR number is needed when you submit your self assessment tax return. It will be sent through the post within about 28 days after your application has been received.

Individual self assessment tax return for a partner

Your individual self assessment tax return can be completed after your SA401 submission has been processed.

The self assessment tax return will have a section for you to enter information relating to your partnership like the partnership UTR number and accounting dates. You will also need to enter your share of the partnerships profit or loss.

If you have more than one partnership a separate page will need to be completed for each partnership.