Registering for Self Assessment

You should register with HM Revenue & Customs (HMRC) if you need to complete a Self Assessment tax return. For example you may have started self-employment or letting property. HMRC will then decide if you need a tax return. If you do, they'll set up your tax records and send you a Unique Taxpayer Reference.

On this page:

Why you might need to complete a tax return

If your circumstances change you may need to fill in a Self Assessment tax return. On the return you tell HMRC about income or capital gains, or claim expenses or reliefs.

For example, you may have:

  • started your own business
  • untaxed income from property or investments
  • expenses to claim (you need a tax return if they're above £2,500)
  • Capital Gains Tax to pay

You will have to fill in a tax return if you or your partner receives Child Benefit and your income is over £50,000.

Check if you need to complete a tax return

Find out more about Capital Gains Tax

Find out more about the High Income Child Benefit charge

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Why and when you need to register for Self Assessment

You need to register for Self Assessment before you complete your first tax return.

When you register you'll give HMRC the information they need to set up the right records for you. This helps to make sure you pay the right amount of tax and National Insurance at the right time.

For other changes in circumstances, simply complete the relevant boxes or supplementary pages on your Self Assessment tax return.

When to register

It's best if you register with HMRC as soon as your circumstances change. The latest you should register is by 5 October after the end of the tax year for which you need a tax return. The tax year runs from 6 April one year to 5 April the next.

If, for example, you have tax to pay on rent from a property in the 2013-14 tax year, you need to let HMRC know by 5 October 2014.

If you register late you may have to pay a penalty.

Take care to tell HMRC about your tax on time (PDF 92K)

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Information you'll need before you register

You will need:

  • your National Insurance number - in most cases you'll already have this, but if you haven't worked in the United Kingdom before you'll need to get one
  • your contact details (and the contact details of your business if you've started self-employment)
  • your 10-digit Unique Taxpayer Reference number, but only if you have previously completed a Self Assessment return - you'll find this on letters or forms sent by HMRC about your tax return
  • the date your circumstances changed

Find out how to apply for a National Insurance number (Opens new window)

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How to register

How you register depends on your circumstances.

If you're newly self-employed

You can let HMRC know about your new self-employment by registering online for business taxes. You'll be asked for information about yourself and your business. HMRC will set up tax records for you using the information you provide, for example:

  • Self Assessment
  • National Insurance
  • PAYE if you have people working for you

A Self Assessment Online account will be set up for you automatically at the same time.

Register your business for HMRC taxes

If you're restarting self-employment

If you've worked for yourself before, HMRC will already have Self Assessment records for you and you should have a Unique Taxpayer Reference already. You can find this on letters and Self Assessment statements from HMRC. You can still re-register online for Self Assessment, using the link below. It's the easiest way to make sure that HMRC have all the information they need. You'll need to register separately for other business taxes, such as PAYE for employers.

Register online for Self Assessment and National Insurance contributions

If you're starting or joining a new business partnership

If you're starting or joining a new business partnership, both the partnership and each partner need to be registered for business taxes.

The partner nominated to receive and send in the Partnership Tax Return can register online. A Self Assessment Online account will automatically be set up for the partnership at the same time. If the partnership is employing other people, HMRC will use the information to set up PAYE records as an employer too.

Register your business for HMRC taxes

If you're not the nominated partner, you still need to register as a partner in the business. HMRC will use the information you send to set up the right Self Assessment and National Insurance records for you.

You can do this online. It will help if you have information about the partnership to hand before you start, for example:

  • address and postcode
  • Partnership Unique Taxpayer Reference
  • Company registration number (if registered with Companies House)

Register online as a partner for Self Assessment and National Insurance contributions.

If a company, trust or another partnership becomes a partner in the partnership, it needs to be registered too. The person responsible for the new partnership, for example, the trustee or company secretary, should complete and sign form SA402.

Download SA402 Register a partner for Self Assessment if they're not an individual (PDF 95K)

If you need a tax return for any other reason

You may need to complete a tax return because your circumstances have changed. For example:

  • you have income from property
  • you or your partner receive Child Benefit and your income is over £50,000
  • you have capital gains that you need to tell HMRC about

In this case you'll need to fill in the online form SA1 Registering for Self Assessment and getting a tax return.

Register for Self Assessment

Check if you need to need to complete a tax return

Find out more about the High Income Child Benefit charge

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What happens once you’ve registered for Self Assessment?

Getting a reference number

Once you've registered for Self Assessment, HMRC will set up your records and send you a letter with a 10-digit reference, called a Unique Taxpayer Reference or UTR. You should keep your Unique Taxpayer Reference in a safe place.

Getting online

If you're self-employed and you registered for business taxes online, accounts will automatically be set up for each HMRC Online Service that you selected. You'll receive an Activation Code for each service and you'll need to activate each one within 28 days.

In all other cases you'll need to sign up for HMRC Online Services yourself, before you can send your Self Assessment tax return online.

Find out more about Self Assessment Online

Sending your first tax return

You'll get a letter, usually in April or May, telling you when you need to send your first tax return. HMRC may get in touch earlier if you need to send a tax return back for a previous tax year. If you don't receive a letter or a tax return, you should contact HMRC.

Telephone or write to HMRC

Find out more about filing online

Other things new businesses need to consider

If you're self-employed as a sole trader or a business partner, you'll usually need to arrange to pay your Class 2 National Insurance contributions straight away too.

You may also need to register for VAT and the Construction Industry Scheme.

Find out about Class 2 National Insurance contributions and exceptions

How and when to register for VAT

What is the Construction Industry Scheme?

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More useful links

Authorising an accountant to deal with HMRC for you

Starting up in business - practical advice from Gov.uk (Opens new window)

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