Self-Assessment Tax Return

Nothing in this page should be taken as legal, professional, accounting or tax advice; we are merely summarising and signposting links to official documentation. You must seek your own guidance from HMRC and professional advisors where necessary.

We caveat our description of the processes here by saying that it was not always possible to get a consistent answer from HMRC’s agents during our multiple interactions.

HMRC (His Majesty’s Revenue and Customs) are the Government department that handle tax collections. There are various scenarios in which you are required to complete a ‘self-assessment’ tax return, i.e. you will need to tell HMRC about your income from different sources, and they will calculate what amount of tax you still need to pay (or in some cases, will be refunded). This could be the case even if your income tax is already being deducted at source by your employer through PAYE (Pay As You Earn).

More information is available on the HMRC website, for example, at this link:

The process for submitting a self-assessment tax return

The steps involved at a high level are as follows:

  • Check if you need to submit a self-assessment tax return
  • Register for a personal tax account online if you can; else register offline (by 5th October after the end of the tax year)
  • Receive your Unique Taxpayer Reference (UTR) in the post (up to 3 weeks after registering)
  • Submit your self-assessment tax return using your UTR, either online or offline, by the appropriate deadline (31st October for offline paper-based tax returns, and 31st January for online tax returns)
  • Pay your tax bill by 31st January to avoid penalties and fines

These are described in more detail on this web page.

Do you need to complete a self-assessment tax return?

HMRC have provided an online tool, which you can use to answer various questions to see if you are required to complete a self-assessment tax return. The tool can be found at: For example, you will most likely be required to complete a tax return in these situations:

  • Your total income is more than £50000 and you are claiming the specific benefit known as Child Benefit (as there is a tax on this)
  • You have income through self-employment
  • You have income earned from working abroad e.g. working online and receiving Ukrainian income, which is not taxed in the UK

See also: Note that if you are self-employed in the UK, you need to have registered as self-employed beforehand; see Setting Up as Self-employed.

Contacting HMRC about self-assessment

HMRC are not the easiest department to communicate with; their phone numbers use complicated voice recognition software to understand what you want to phone about. Just be patient and tell the system ‘I want to speak to an adviser’, then when they ask you what you need help with, say ‘I want help with self-assessment / VAT / etc’ (i.e. whatever you are ringing for help about), eventually it will transfer you to a human being. It’s worth knowing that when you do get through to a person, you can ask to speak to a translator.

For self-assessment queries, you can call 0300 200 3310. If your query is more complex, then they should transfer you to a team who can help you.

You can also use online webchat. Go to, and in the ‘Ask HMRC online’ section, select the link to launch the Digital Assistant. To begin with, you will be talking with a chatbot, but you can ask to be transferred to speak to an adviser. This is actually a pretty good option, as you can use translation tools to ask questions and understand the answers.

Registering online for self-assessment tax returns

Note: if you need to set yourself up as self-employed in the UK, you should follow a different process which also sets you up for self-assessment at the same time. See Setting Up as Self-employed.

If HMRC’s online tool says that you are required to fill in a self-assesment tax return, you can do this either online or offline. The online route is preferable for two main reasons:

  • You have an extra 3 months to submit your tax return compared to using offline methods
  • It’s easier to complete the tax return online as the sections you fill in will be tailored to your circumstances

The basic steps for doing this online are:

  • Set up a personal tax account, using an email address and UK mobile to register and receive a Government Gateway User ID (a 12 digit number), which you use to log on with
  • Verify your real life identity online by answering a number of questions and providing information that only you know the answer to
  • Once your identity is verified, you will receive your 10 digit Unique Tax Reference (UTR) in the post; this can take up to 3 weeks
  • Once you have your UTR, you can fill in, check and submit your self-assessment tax return online by logging into your personal tax account using your Government Gateway User ID

In order to verify your identity online, you can choose to provide 2 of the following pieces of information:

  • Information based on your finances, such as questions about your credit cards or bank accounts
  • UK driving licence
  • Information based on your work income, such as questions about your P60 or recent payslip from employer

There is also an option to use a mobile app to confirm your identity, together with a document such as a BRP. The exact identification methods used may vary from this description, so follow the instructions to choose what seems the most relevant option for you. Answer any questions asked as accurately as possible in order to pass identification. (Note that if HMRC sent you a letter earlier in the year saying you were owed a tax refund, you may have already managed to successfully register and set up your online tax account.)

Without such information or types of identification, it may not be possible to complete the online identity verification requirements. If you cannot register online, you will need to register offline for your UTR and file a paper-based tax return (pay attention to the different, earlier deadline!), but hopefully you will be able to get through the process once you have been in the UK for a while.

Note: it should always be possible to complete the task you need to do by phone or by paper if you do not have the ability to register online.

If you cannot register online for self-assessment tax returns

If it is difficult to register online due to the identity verification requirements required, there are a couple of other ways given to do this.

Once you have been registered, the system will create an ‘individual self-assessment record’ for you, and within 2 to 3 weeks, you should get a letter with your 10-digit number UTR (Unique Taxpayer Reference). You will need to use your UTR to file your tax returns later on in the year when they’re due.

You should register for self-assessment and get your UTR set up some months before your tax return is due.

How much does it cost to get a UTR?

It is absolutely FREE. You really do not need to pay anyone (such as an accountant) just to get a UTR. Just follow the processes above, and learn as you go.

Filing your self-assessment tax return and deadlines

You can fill in and submit your self-assessment tax return at this link: You can also create a Government Gateway User ID using this link if you did not create one earlier.

This short video explains the process for filing your return. The important step is ‘View your calculation’, which you can use to see how any tax you owe is calculated.

Alternatively, if you were not able to register online, you should be sent a paper-based tax return form called SA100 to fill in and send back to HMRC.

You will need your UTR to submit your tax return in both cases.

An online tax return usually would need to be submitted by the 31st January following the end of the tax year. However, a paper tax return must be sent earlier, by the 31st October following the end of the tax year. See

For example, if you are filing your tax return for the tax year 6th April 2022 to 5th April 2023, your online tax return deadline would be 31st January 2024. A paper tax return must be sent earlier, by 31st October 2023.

Income declared should be for the tax year it is earned i.e. it’s not possible to include income from a different tax year in a tax return.

All taxes owed would need to be paid by the 31st January following the end of the tax year. There are penalties for paying your tax late, and interest charges on outstanding tax owed.

If you are departing for Ukraine before the deadlines for submitting your tax returns, refer to Going Back to Ukraine – you will need to contact HMRC to pay any tax owed when you leave.

If you miss the tax return submission deadline

If you did not realise how long it might take to get the paperwork together or couldn’t register online and missed the deadline to submit your paper-based tax return by 31st October, you may incur penalty charges. In this case, we asked HMRC what to do. They said that you could try to appeal, as some leniency is provided towards those filing tax returns for the first time and who may have been unaware of the requirements or unable to register online.

Receiving Ukrainian-based income

If you are receiving income in Ukraine, for example, through online work for a company based in Ukraine, or or self-employment work, you may also need to complete a tax return via the ‘self-assessment’ process. This is a more complicated situation and it would be best to speak to HMRC about this on 0300 200 3310. They will need to transfer you to an internal team known as the ‘technical team’.

See also the published Government guidance:

This charity organisation may be able to help you understand what you need to do as well:

  • TaxAid – they can be phoned on 0345 120 3779