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How to Register for Self Assessment

Use this guide to check if you need to register for self assessment, how to apply and which HMRC form you need as well as what to expect once you’ve successfully registered.

Friendly Disclaimer: Whilst I am an accountant, I’m not your accountant. The information in this article is legally correct but it is for guidance and information purposes only. Everyone’s situation is different and unique so you’ll need to use your own best judgement when applying the advice that I give to your situation. If you are unsure or have a question be sure to contact a qualified professional because mistakes can result in penalties.

Do You Need to Register for Self Assessment?

You need to register for self assessment if you have received income that you have not paid tax on, but should have. Not all types of income are taxable so HMRC don’t need to know about all types of earnings. Here are some common types of UK taxable income often paid to individuals without any tax deducted and need to be reported to HMRC:

In other cases, individuals may find they need to register for self assessment to report their income because they:

Find out more about different types of taxable income in this separate guide to help check whether you need to register with HMRC.

If you already fill in a tax return for another reason then you don’t need to register again. If you do, HMRC will set you up on their system for a second time and expect two tax returns from you. Instead, you should complete a CWF1 Form online.

What Happens Once You’re Registered for Self Assessment

Once registered you’ll need to fill in a tax return by the 31 January each year with details of your income for the previous tax year. The tax year runs from 6 April to 5 April each year. That means a tax return due by 31 January 2023 relates to income earned from 6 April 2021 to 5 April 2022.

In addition to completing a tax return, you’ll be expected to pay any tax due by the same date. Some individuals may need to make an additional tax payment by 31 July, known as a payment on account. If you’re self-employed you should make yourself aware of payments on account because of the potential effect on your cash flow. Read this guide to find out more about these tax payments and see some examples.

How to Register for Self-Assessment

Registering is simple enough to do yourself and the easiest way to apply is to go online, set up a .GOV account and submit the registration form online:

How to Register for Self Assessment

  1. Visit the HMRC website

    Head over to the HMRC website and choose the option to “Register Online”how to set up as a sole trader

  2. Set Up a Government Gateway Account

    This is the account where you’ll manage all your taxes. HMRC will automatically generate a 12 digit number which you’ll need to use as your login and let you choose a password.

  3. Enrol for Self Assessment

    Complete the HMRC form to register for self-assessment. You’ll need to share your personal details, details about your reasons for registering to complete a tax return and make a declaration that everything you have entered is true.

  4. Wait for HMRC to Review Your Application

    HMRC will review your application once you submit it. Within the next 10 days they will send you out a UTR number to be posted to you (can take up to 10 days). It’s a 10 digit 10 ID number that you’ll need to keep safe in the event you need to prove you are a sole trader, speak with HMRC and manage tax returns.

  5. Enter Your Activation Code

    Finally, you’ll also be sent an activation code for your government gateway account as part of the verification process. It can take up to 28 days for this to be sent but make sure you enter it as soon as you receive it because it will expire.

  6. What Happens Next

    Once registered with HMRC you’ll need to manage your own taxes which means declaring your income once a year on a tax return, by 31 January and paying any tax you owe once and possibly a July tax payment, depending on your circumstances.

How Long Does Registration Take?

HMRC’s guidance says the registration process takes 7 – 10 days to complete. However, there can be delays with these timescales. To get an up to date estimate of how long your application will take you can call HMRC on 0300 200 3310.