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Navigating the Self Assessment process can seem daunting, but it doesn’t have to be. Whether you’re newly self-employed, a seasoned freelancer, or earning extra income from your side hustle, understanding how to manage your tax responsibilities is crucial. This guide breaks down everything you need to know about Self Assessment, from who needs to file and key deadlines to what happens if you miss them.
Self Assessment is the system used by HMRC to collect Income Tax from individuals and businesses whose taxes aren’t automatically deducted through PAYE (Pay As You Earn). It’s typically used by self-employed people, landlords, and anyone with additional income such as dividends. Rather than HMRC calculating your tax, you report your income and expenses for the tax year and calculate how much tax you owe. The process involves completing an annual tax return online or on paper, with deadlines falling on 31 October (for paper returns) and 31 January (for online returns).
Generally speaking, anyone who receives an income that isn’t taxed at
source should complete a self-assessment. This might include income
earning through contracting or freelancing, but could also mean income
from rental properties or investments, or receiving untaxed income
through tips and commission. Anyone earning a total taxable income over
£150,000 through PAYE for the 2023-2024 tax year onwards also needs to
complete a self-assessment, with the threshold having increased from
£100,000.
If you’re not sure whether you need to complete a tax return, you can check here on the gov.uk website.
You’ll need to file your Self Assessment by 31st January after the end of the tax year it applies to (tax years run from 6th April to 5th April). However, if you’re employed, you can submit your Self Assessment as soon as you receive your P60. If you’re a sole trader, you can file your Self Assessment as soon as the tax year ends. There’s plenty of reasons to get a head start, too – you’ll have peace of mind knowing it’s ticked off your list, you’ll know what you owe so you can budget for the year ahead, and you’ll find out sooner if you’re owned a refund (and get it sooner, too!)
Registering through gov.uk is pretty straightforward. You’ll just need a few details, including basic personal information like your National Insurance number, the date you started your business, and information about the type of work you do. The entire registration and set-up process for SATRs can take up to 20 working days, so you should do so well in advance of the deadline (5th October in your second tax year) to avoid any headaches.
Follow the links to register online, or fill and print the postal form.
Complete your registration. You’ll receive your Unique Taxpayer Reference (UTR) alongside instructions to create your Government Gateway account.
Activate your Government Gateway account. You’ll receive an activation code in the post. It is important to keep your login details safe as you will need these details to complete your self-assessment tax return.
If you’re submitting your self-assessment tax return online, follow the process below to submit your tax return:
Sign in to your Government Gateway account.
Select the 'Complete your tax return' link under 'Self-Assessment'.
Complete the information requested as prompted.
Check your return is correct, view your tax liability, and submit when ready.
If you’re completing a paper tax return via post, you will need to download and print form SA100 from the .gov website. If you’re not able to download the forms yourself, you can call HMRC and ask to have them sent to you.
Remember: If you do decide to submit your tax return by post, be sure to allow plenty of time to account for potential delays, and keep your own copies along with proof of postage. As we mentioned earlier, your deadline also falls before that of online tax returns, and must be submitted by 31st October.
To complete your tax return, you will need the following information:
Register for Self Assessment: 5th October
Complete paper tax return: 31st October
Complete online tax return: 31st January
Pay tax: 31st January
Who's it for?
Self-employed, Freelancers, First-time filers, E-commerce, Contractors, Investors, Digital Nomads, Landlords, PAYE (over £100k), Construction workers (CIS)
If your tax return is late, HMRC will charge an automatic £100 fine, even if you don’t owe any tax. After that, you could start to face daily penalties along with a percentage of your tax liability. To avoid these penalties, it’s crucial to file on time, and if you're struggling, you can request an extension which may be granted in limited circumstances. You can also call the Self Assessment helpline on 0300 200 3310.
If you realise you may have made a mistake whilst submitting your SATR online, you can go back and make changes up until the filing deadline for the next tax year. In other words, up to a year after the initial deadline for submission. You can also save your progress as you go, giving you plenty of time to think about your answers or return and correct any previous answers.
Luckily, help is available for those who are struggling financially. If you can’t pay your tax in full, HMRC may allow you to set up a payment plan, known as a ‘Time to Pay’ arrangement. However, it’s important you speak to HMRC as soon as possible to inform them of any issues, and that you still complete your Self Assessment tax return on time. More help and advice can be found here.
Payments on account are advance payments you make twice a year
towards your Self Assessment tax bill. This process is designed to help
taxpayers stay on top of their payments as well as avoid paying tax in
arrears. This is calculated based on your previous year's income tax and
Class 4 National Insurance contributions.
The estimated amounts are split into two equal payments, with the first
due by 31st January and the second due by 31st July, which equate to 50%
of your previous year’s tax bill. For example, if your tax bill for the
previous year was £5,000, your payments on account for the current year
would be £2,500 each.
If your actual tax bill for the current year ends up being higher or
lower than the estimated amount, HMRC will adjust it. You may need to
make a balancing payment by the following 31st January if you owe more,
or you’ll receive a refund if you’ve overpaid.
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