2025’s nasty surprise: HMRC coming after casual online sellers

31 January marks the deadline for submitting self-assessment tax returns to HM Revenue and Customs (HMRC). With reports indicating millions are yet to file, a race against time is underway to avoid any hefty penalties.

In 2025 there has also been a change which could result in a significant portion of the UK population being liable for tax on a self-assessment basis for the first time. Online platforms like eBay and Vinted must now provide HMRC with sales information for individuals selling thirty items or more or who have earned at least £1,700 from sales.  HMRC will analyse the sales data and compare with individual tax returns. Thousands of people on PAYE, who have never registered for self-assessment, will receive letters from HMRC in the coming months inviting them to complete self-assessment returns and pay additional tax.

The annual self-assessment process requires individuals with complex tax affairs, including the self-employed, landlords, and high-income earners, to declare their income and calculate their tax liability. While many taxpayers diligently file their returns in advance, a significant proportion habitually leaves it to the last minute. This year is no different, with HMRC facing a potential deluge of submissions in the final hours.

The consequences of missing today’s deadline are severe. Automatic penalties are imposed for late filing, starting with a £100 fixed penalty. These escalate the longer the return remains outstanding, with additional charges after three, six, and twelve months. Interest is also charged on any unpaid tax, compounding the financial burden. In the most serious cases, HMRC may even pursue legal action.

HMRC has been urging taxpayers to utilise their online services to file returns, emphasising the efficiency and accuracy of the digital system. However, with millions still to submit and the deadline looming, the online platform may experience increased traffic and potential delays.

For those scrambling to meet the deadline, here are some key points to remember:

• File online: HMRC’s online system is the fastest and most efficient way to submit your return.
• Gather your documents: Ensure you have all the necessary information, including your National Insurance number, income records, and expense receipts.
• Accurate calculations: Double-check your calculations to avoid errors that could lead to further penalties.
• Seek help if needed: HMRC offers online resources and contact channels for taxpayers needing assistance. However, expect potential delays in response times due to the high volume of inquiries.

This year there was also , online platforms such as eBay and Vinted must tell HMRC about sales information from people selling 30 items or more or who earned at least £1,700.

The authority will assess those details against individual tax returns.

For those who genuinely cannot submit on time due to exceptional circumstances, HMRC advises contacting them immediately. They may be able to agree on a payment plan or waive penalties in certain situations. However, this is assessed on a case-by-case basis, and taxpayers will need to provide compelling evidence to support their claim.

The message from HMRC is clear: time is running out. With the deadline upon us, individuals must act swiftly to submit their returns and avoid the penalties of late filing. Don’t leave it any later – submit your tax return today and ensure compliance with HMRC regulations.