HM Revenue and Customs (HMRC) has issued a deadline reminder for those who are due to complete a self-assessment tax return for the 2022/23 tax year.

Anyone who is new to the process has until October 5 to register themselves. Due to the surge in Britons taking on additional money-making ventures to help with the cost of living, many more may find themselves liable to pay additional tax.

According to HMRC, new self-assessment customers could be someone who has set up a side hustle to earn money in addition to their day job or disposed of cryptoassets; they could be newly self-employed or they could be a new landlord renting out property. As of July 2023, there were around 4.24 million self-employed workers in the UK.

Whatever the circumstances, HMRC says if a customer has “any income that they have not already paid UK tax on”, they will need to register for a self-assessment.

Myrtle Lloyd, HMRC’s director general for customer services, said: “If you are new to Self Assessment and unsure how the process works – HMRC is here to help.

“We have a wealth of resources and guidance available on GOV.UK to help customers register, sign up to the online services and complete their tax return.

“We want to help customers get their tax right first time, just search ‘Self Assessment’ on GOV.UK to find out more.”

To quickly assess whether they need to complete a tax return, customers can use HMRC’s online checking tool. From here, they can use the step-by-step guide to check what they need to do to file it.

After registering for the assessment, customers will receive a Unique Taxpayer Reference, which they will need when completing their return.

The deadline to file the return online and pay any tax owed for the 2022 to 2023 tax year is January 31, 2024. According to the tax body, 96 percent of customers filed their returns online last year.

Filing online means customers don’t have to complete it all at once. It allows people to save their progress and finish it later, while also having “added reassurance” that HMRC has received their form when they press submit.

If customers think they no longer need to complete a self-assessment tax return for the 2022 to 2023 tax year, they need to tell HMRC before the January 31 deadline to avoid any penalties.

A late filing penalty of £100 is issued if a tax return is one day late. People have to pay even more if it’s later, as well as interest, making it a costly mistake to make.

HMRC also stressed the importance of being vigilant to scam risks and urged customers to “never” share their HMRC login details with anyone, including a tax agent, if they have one.