Self Assessment

Register for Self Assessment

When and how to register for Self Assessment tax.

UK-wide
Guide summary

You must register for Self Assessment if you earn income beyond PAYE, are self-employed, or a partner in a business. This gives you a Unique Taxpayer Reference (UTR) for filing tax returns. Register by 5 October following the end of the tax year you started earning this income to avoid penalties.

  • Register for Self Assessment if you earn over £1,000 self-employment income
  • Register if you're a business partner, landlord, or high earner
  • Deadline to register is 5 October after the tax year you started
  • Get a 10-digit UTR by post within 10 working days
  • Receive an activation code separately for online account setup
  • File online tax return and pay tax by 31 January
  • Late registration can lead to penalties for late filing or payment
  • Set up a separate Government Gateway account for personal and business taxes
On this page
UK-wide

Related guides in Tax & Finance

You must register for Self Assessment if you're self-employed, a partner in a partnership, or have other income to declare. You'll get a Unique Taxpayer Reference (UTR) which you need to file your tax return.

Who must register for Self Assessment?

You must register if you:

  • Self-employed sole trader - earned more than £1,000 gross income from self-employment
  • Partner in a business partnership - regardless of income level
  • Company director - unless only receiving PAYE salary with no other income
  • Landlord - receive rental income from property
  • High earner - income over £100,000 (even if all PAYE)
  • Child Benefit claimant - you or partner earn over £50,000
  • Foreign income - receive income from abroad
  • Savings/investments - untaxed income over £10,000
  • Capital gains - sold assets above the annual exempt amount

Registration deadlines

You must register by 5 October following the end of the tax year in which you started your business or received untaxed income.

Example: If you started self-employment in August 2026 (tax year 2026/27), you must register by 5 October 2027.

Late registration penalties: No automatic penalty for late registration, but you may face penalties if this causes late filing or payment.

What you'll receive

  • UTR (Unique Taxpayer Reference): 10-digit number sent by post within 10 working days (21 days if abroad)
  • Activation code: Separate letter with code to activate your online account

Keep your UTR safe - you'll need it for all Self Assessment dealings, applying for mortgages, and some business contracts.

  1. 1

    Check if you need to register

    Use HMRC's tool to check if Self Assessment applies to you.

  2. 2

    Gather your information

    You'll need your National Insurance number, business start date, and business address.

  3. 3

    Create Government Gateway account

    If you don't have one, create a Government Gateway ID first.

  4. 4

    Register online

    Complete the online registration - takes about 10 minutes.

  5. 5

    Wait for your UTR

    HMRC will post your UTR within 10 working days (21 days if abroad).

  6. 6

    Activate your account

    Use the activation code from the second letter to access Self Assessment online.

Register for Self Assessment (opens in a new tab)