Jazz singer Billie van der Westhuizen started using Vinted about six months ago to sell clothes and shoes she hadn’t worn for ages.

“I got really into it and was selling loads of stuff,” she says. “Then I got a message saying I needed to enter my National Insurance number. It wasn’t clear at all why it was asking.”

Vinted users who have sold 30 items or made £1,700 in a year are being asked for their NI number, leaving many like Billie confused and some panicking that they will have to pay tax.

But this is not about any tax changes – it’s due to reporting rules for websites and apps that allow users to sell goods or services, including eBay, Etsy, Depop and AirBnb.

Billie, 30, from London, says she entered her NI number as prompted but in hindsight was not sure what it was about.

“I just sent it but I thought there’s no way they could tax the amount of money I’ve made off this,” she says.

“If I was making thousands maybe, but I reckon I’ve made maybe £500 and I’m selling things for less than I paid for them.”

The pop-up alert Billie received sends Vinted users to a form asking for their name, address and NI number “as required by UK law”.

Some Vinted sellers have posted screenshots of the messages on TikTok and Instagram asking if they have to give their details, and if they do, will they be taxed.

One user posted on Reddit: “Vinted is asking for my National Insurance number, does this mean I have to pay taxes? I barely make money on Vinted – what happens if I ignore this?”

Chartered accountant Abigail Foster says while a lot of people may panic when asked for tax information by Vinted, for most users this is nothing to worry about.

“If you’re simply selling your own second-hand clothes or household items, you won’t owe any tax, even when Vinted shares that data with HMRC,” she says.

“This rule is aimed at people who are effectively running a resale business, not those decluttering their wardrobes.”

It would be very easy for HMRC to tell if someone was trading by checking for multiple listings of the same product or items bought and quickly resold for higher prices, she adds.

New reporting requirements for digital platforms came into effect on 1 January 2024 with the government saying they would help it “bear down on tax evasion”.

Vinted sellers reported receiving in-app messages asking for their NI number around this time last year.

Information must be shared with HMRC by the end of the calendar year that sellers hit the 30 item or £1,700 threshold, according to Vinted.

An HMRC spokesperson said: “People remain responsible for their own tax affairs, and for assessing whether they need to complete a tax return to report trading income.

“As your side hustle grows, any unpaid tax might come under the spotlight.

“This could lead to an unexpected and possibly very large tax bill if you haven’t told us about the extra money you’ve been earning. That’s why it’s really important to stay on top of your tax affairs.”

Research commissioned by HMRC in 2022 suggested around one in 10 UK adults participated in what it called the “hidden economy” – earnings that are entirely or partially concealed from the tax authority to avoid paying taxes.

• Platforms must tell HMRC about anyone who sells more than 30 items or whose total sales hit £1,700 in a year
• This does not automatically mean these people have to pay tax
• Selling your own clothes or other items is not taxable if you’re selling them for less than you originally paid as you are not making a profit
• Tax only applies if you are buying stock to resell, or making more than £1,000 in profit per year
• If you sell an item for more than £6,000, you may need to pay Capital Gains Tax.
• You can use HMRC’s online tool to check if you need to tell the authority about your income