Registering for Self Assessment – a guide for the self-employed

If you’re new to the world of self-employment, you may be wondering how you pay income tax. The first thing you’ll need to do is register for Self Assessment, then you’ll be able to complete your annual tax return. 

You’ll need to register for Self Assessment before the 5 October deadline and make sure you provide all the correct information. If you don’t, you could leave yourself open to receiving a penalty from HMRC.

Before you complete your online Self Assessment tax return, it’s important you understand how the registration process works and what you need to do. 

In this guide we’ll cover:

• what is a Self Assessment?
• who needs to register for Self Assessment
• when you need to register for Self Assessment
• a step-by-step guide to registering for Self Assessment
• what to do after registering for Self Assessment
• common issues when registering for Self Assessment
• registering for Self Assessment FAQs

What is a Self Assessment?

If you’re self-employed, you pay income tax through Self Assessment. This means you have to complete and pay your tax return by 31 January each year. 

If you’re employed, you don’t have to complete a Self Assessment. Your income tax is deducted by your employer and paid through the PAYE system.

As with those paying income tax through PAYE, Self Assessment taxpayers are taxed based on their annual earnings. You have the same tax-free personal allowance (£12,570) and are subject to the same income tax rates.

However, if you pay tax through Self Assessment, you can claim self-employed expenses to reduce your final tax bill.

Self Assessment registration – who needs to do it?

It’s likely you’ll need to register for Self Assessment if you:

• are self-employed as a sole trader and earned more than £1,000
• are a partner in a business partnership
• need to pay capital gains tax after selling an asset
• need to pay the High Income Child Benefit Charge
• earn money from renting out a property

You may also need to register if you have untaxed income from:

• tips and commission
• savings, investments, and dividends
• money earned abroad

If you’re not sure whether you need to register, you can check on the government website.

How to register for Self Assessment in 5 steps

Registering for Self Assessment is very important for new business owners, but it should be a fairly quick process. 

Follow our five registration steps to get started.

Step 1: Check if you need to register

If you think you need to register for Self Assessment but aren’t completely sure, you can check on the government website.

By answering a few questions about your business, you can get confirmation on whether you need to register. 

Completing this step first means you won’t waste time registering for Self Assessment if you don’t need to. 

Step 2: Create a Government Gateway account

Once you’ve confirmed that you need to register for Self Assessment, you’ll need to create a Government Gateway account.

Once you’ve signed in to your Government Gateway account, you’ll need to select ‘Add a tax to your account to get online access to a tax, duty or scheme’.

Step 3: Complete the online registration form

Next, you’ll need to register for both Self Assessment and Class 2 National Insurance.

You can do this by completing the registration form through your Government Gateway account. If you’re self-employed, you’ll need to complete a CWF1 form and if you’re a landlord, you’ll need to complete the SA1 form.

You’ll need to provide personal details as well as details about your income sources.

If you can’t register online, you can complete the relevant form and send it by post to:

Self Assessment
HM Revenue and Customs
BX9 1AN
United Kingdom

Step 4: Receive your Unique Taxpayer Reference (UTR) number

Once you’ve completed your registration form, you’ll receive your 10-digit Unique Taxpayer Reference (UTR) number – you’ll need this number to submit your tax return.

HMRC sends out UTR numbers by post within 15 working days (or 21 working days if you live abroad). If you use the HMRC app, it’s likely you’ll get your UTR number sooner.

With this in mind, make sure you leave enough time before the registration deadline to avoid a Self Assessment late filing penalty from HMRC.

Step 5: Set up your online tax return account

The next step is to activate your online tax account using your UTR number. You may also be sent a separate activation code if you registered online.

You’ll then be fully registered and able to complete a Self Assessment tax return.

Read more: Self Assessment payment on account – a guide for the self-employed

What to do after registering for Self Assessment

Once you’re registered, you’ll need to think about completing your Self Assessment tax return for the relevant tax years. 

Keep in mind key dates, such as: 

• 31 January – online tax return deadline
• 31 October – paper tax return deadline (this is being phased out as part of Making Tax Digital)
• 5 April – end of the tax year
• 6 April – start of the tax year

It’s important to keep track of your income and expenses so that you have all the information you need to complete your tax return. Read our guide to bookkeeping for more information.

Common issues when registering for Self Assessment 

Some of the most common issues for new businesses registering for Self Assessment include:

• delays in receiving a UTR number – you won’t be able to submit a tax return without one. The quickest and easiest way to get one is by using the HMRC app
• problems creating a Government Gateway account – some people may not be able to set up an account (for example if they already have one). You can call HMRC for help or register by post as an alternative
• falling for an HMRC scam – if you respond to correspondence from someone purporting to be HMRC, you may think you’ve registered for Self Assessment when you haven’t

These issues can delay the tax return process so make sure you leave enough time ahead of the Self Assessment registration and tax return deadlines to avoid a fine from HMRC.

Registering for Self Assessment FAQs

Can I register for Self Assessment if I don’t have a National Insurance number?

You usually need a National Insurance number to register for Self Assessment. 

If you don’t have one, there may be some cases where you can still register. If this is the case, you should contact HMRC for more information.

Can I register for Self Assessment over the phone at HMRC?

Yes, you can register for Self Assessment by calling HMRC on 0300 200 3310. You’ll need to have all your personal and business details to hand. 

It can be much quicker to register for Self Assessment online or using the HMRC app.

Should I deregister if I am no longer self-employed?

Yes, you should deregister from Self Assessment if you’re no longer self-employed. By doing so, you can avoid paying tax or receiving late filing penalties for tax you don’t owe. 

You can deregister from Self Assessment using your Government Gateway account.

Do I need to register separately if I have multiple self-employed businesses?

No, you don’t need to register separately for Self Assessment if you have multiple self-employed businesses. 

When completing your tax return, make sure you separate all your income and expenses for your different businesses. And remember to declare your businesses on your tax return.

More tax guides for small businesses

• Self-employed tax – income tax rates explained
• Can HMRC check your bank account without your permission?
• How early can I submit my tax return?
• How to amend a Self Assessment tax return