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Join Which? MoneyDon't miss the deadline to register for self-assessment – do you need to file a tax return?
First-time filers must register with HMRC by 5 October
If you need to pay tax by self-assessment and it’s your first time doing so, the deadline for registering with HMRC is 5 October.
Once registered, you will be assigned a Unique Taxpayer Reference (UTR) number. You will need this to file your 2021-22 tax return – and for any future tax years – before 31 October for paper forms, or 31 January 2023 if you're submitting online.
It’s your responsibility to declare all your taxable income, so even if you haven't had a reminder or request from HMRC, it doesn't necessarily mean you don't have to file a tax return.
Here, Which? explains how to register for self-assessment, and reveals the sources of income you might not know you have to declare.
Who needs to register for self-assessment?
See our guide for a long list of people who'll need to pay tax by self-assessment, as well as some lesser-known types of income you'll have to declare below.
Child benefit payments
Many parents who receive child benefit can get caught out, as they may not realise their tax obligations.
Child benefit refers to the flat-rate monthly government payments for those who are responsible for children. The payments aren't means-tested, but households where one or both parents or partners have an income of more than £50,000 a year are required to pay some or all of this benefit payment back via a self-assessment tax return – even if they wouldn't usually submit a tax return for any other form of income.
This tax repayment is known as the high-income child benefit charge. It's paid at a rate of 1% of the benefit for every £100 of income between £50,000 and £60,000. If either parent earns £60,000 or more, the full amount of child benefit must be repaid.
If you want to get the National Insurance credits that come with child benefit (which is handy for any parents taking time out of work to look after children) but don't want to deal with the high-income child benefit charge, it's possible to continue to claim child benefit, but simply opt out of receiving the payments.
Self-employed income support scheme (SEISS) grants
The SEISS was a government scheme for self-employed workers whose earnings had been reduced due to the coronavirus pandemic. If you received any of these government payments after 6 April 2021, you will need to declare it on your tax return as part of your 2021-22 income.
Income from online platforms
Innovative new ways to earn money have become increasingly popular over the past few years – and, because they're new, could be in danger of getting missed off tax returns.
For instance, income from online platforms such as Patreon, Twitch and Kofi must be declared. The sites are commonly used by content producers who receive a 'donation' for their work – but despite being given this label, the money should be counted for income for tax purposes.
The same goes for money made from selling items on online marketplaces such as eBay, Depop and Vinted. There's a tax-free £1,000 trading allowance that can be applied to this kind of income, but anything over that amount is taxable.
Money made from your home
If you rent a room in your home via the rent-a-room scheme, and earn more than the annual tax-free allowance of £7,500, you'll need to declare your income.
The same goes for income received from renting your home out on sites like Airbnb. There's a £1,000 property allowance that can be used for money you make from your home, including other activities such as renting out your driveway. But if you earn more than £1,000 in a tax year, this will be taxable.
5 types of income you mustn't miss on your tax return
How to register for self-assessment
Registering for self-assessment is relatively straightforward. HMRC's online guide can take you through the process; simply select whether you're self-employed, not self-employed, or a partner or partnership.
You'll need to set up a government gateway account if you don't already have one.
Once you've filled out the relevant forms, you'll be posted your 10-digit Unique Taxpayer Reference (UTR) number. It will take up to 10 working days to arrive if you're in the UK, or up to 21 working days if you're abroad.
You can then use your UTR number to set up your online tax account, and sign up for self-assessment online. You'll then be posted an activation code within seven working days (21 abroad), which you'll need to complete the sign-in process, and finally submit your tax return any time before the deadline.
You'll only need to register for self-assessment once. If you've submitted a tax return in a previous tax year, you shouldn't have to go through the process again.
Find out more: what is a UTR number?
Is there a fine for missing the registration deadline?
While you might not receive a penalty for failing to register for self-assessment by 5 October, you may be fined if registering later means you miss the tax return and tax payment deadline.
If you're just a day late to submit your tax return, you could be fined £100, and your tax bill will have interest added to it every day that it's late.
Find out more: late tax returns and penalties for mistakes
Submit your tax return with Which?
When submit your tax return – which is due by 31 January 2023 – the Which? tax calculator can help you tot up your tax bill, and suggests expenses and allowances that you might have forgotten.
You can declare income from a range of sources, and even use the tool to submit your return directly to HMRC once you're satisfied that everything's been included.
