How do I register for self-assessment with HMRC?
Answered 11 March 2026
HMRC Guidance / Practice
Based on the available HMRC guidance, here is how to register for Self Assessment, depending on your circumstances:
Which form to use
The correct registration form depends on your situation:
| Circumstance | Form to use |
|---|---|
| Self-employed individual | Form CWF1 |
| Not self-employed (e.g. company director, landlord receiving UK property income) | Form SA1 |
| New partnership | Form SA400 |
| Individual partners | Form SA401 |
| Non-individual partners (e.g. a company) | Form SA402 |
Key requirements
- Both Form CWF1 and Form SA1 require a valid National Insurance Number (NINO). The application cannot be processed without it.
- For the small number of individuals who do not have a NINO (e.g. foreign nationals), separate guidance applies.
How to register
Customers can register for Self Assessment via multiple routes, including the Online Tax Registration Service (OTRS) (where registration for online services is automatic), or by submitting a paper form. HMRC's main guidance page for individuals is at: https://www.gov.uk/topic/personal-tax/self-assessment.
Partnerships — timing
Partnership registration forms should be filed with HMRC within six months of the end of the tax year of commencement.
Note: LLPs and Limited Partnerships are automatically registered with HMRC upon registering with Companies House (from 25 October 2010), so Form SA400 is not required for them — but partner details must still be filed using Forms SA401/SA402.
Completion of registration
Registration for Self Assessment is complete when a Unique Taxpayer Reference (UTR) is allocated.
⚠️ The retrieved sources are primarily drawn from HMRC internal manuals (aimed at HMRC staff and agents) rather than the public-facing GOV.UK registration journey. For the step-by-step online registration process as an individual, please visit: https://www.gov.uk/topic/personal-tax/self-assessment
Citation sources
Guidance on registering partnerships and partners for Self Assessment and NICs purposes (using Forms SA400, SA401 and SA402) can be found at SAM100136. Form SA400 is used to register a new partnership. Forms SA401 should also be completed and returned to HMRC to register the individual partners; Form SA402 is used instead where the partner is not an individual, e.g. a company. The forms can be accessed on HMRC’s website (Archived page). Registration forms should be filed with HMRC within six mon
To enable HMRC to provide a better service that is simple to manage, the Central Agent Authorisation Team (CAAT) in NIC&EO set up all new Self Assessment (SA) cases. The following forms are used to register for SA and are processed by CAAT Form CWF1 for those who wish to register as self employed Forms SA400 / SA401 / SA402 for those who wish to register partnerships and partners Form SA1 for those who wish to register for SA who are not self employed or in business However, due to the complexit
When the Transactions in UK Land rules apply the company or individual's income will be treated as arising from a trade of dealing in or developing UK land. Both UK resident and non-UK resident companies and individuals will need to notify chargeability and register to pay tax. There are no separate filing or payment rules for this legislation. The normal self-assessment regime for income tax and corporation tax will apply. Non-UK resident companies need to register for UK corporation tax using