Quick disclaimer first: this isn’t tax advice. The UK rules on selling online are genuinely confusing, and most of the panic going around is based on a misunderstanding. So here’s the plain version.

If you sold stuff on Vinted, eBay or Depop last year and got a message asking for your National Insurance number, you probably froze for a second. A lot of people did. Here’s what’s actually happening, because for most sellers the answer is: nothing. You owe nothing and you do nothing.

Why HMRC suddenly knows about your sales

Since 1 January 2024 there’s a rule called the Reporting Rules for Digital Platforms. Platforms like Vinted, eBay, Depop, Etsy, Airbnb and Uber now have to collect seller data and report it to HMRC once a year. The first report covered all of 2024 and was due by 31 January 2025. Then it repeats every January.

That’s why you got the pop-up asking for your name, address and National Insurance number. The platform has to send HMRC your details plus your total sales and number of transactions. They also send you a copy of whatever they reported.

This isn’t a new tax. The rules on what you owe haven’t changed at all. The only thing that changed is that HMRC now sees the data automatically instead of relying on people to declare it.

One thing worth saying clearly: being reported does not mean you owe tax. It’s a data-sharing requirement. If you were only selling your own old clothes, you typically owe nothing.

When does a platform actually report you?

For selling goods, there’s a small-seller exclusion. The platform only has to report you if, in a calendar year, you either:

Trigger	Threshold
Number of sales	30 or more
Total received	More than ~£1,700 (more than €2,000)

If you stay under both (fewer than 30 sales and under ~£1,700), the platform doesn’t have to report you for goods. These limits are per platform, per calendar year, and GOV.UK explains how to check whether your online platform income needs reporting.

Services work differently. If you’re letting a place on Airbnb, driving for Uber, or renting things out, there’s no minimum. Reporting starts from the first payment.

But again, hitting the threshold just means HMRC gets the data. It doesn’t decide whether you owe anything. That’s a separate question, and it’s the important one.

The line that actually matters: your stuff vs a business

Here’s the bit that clears up most of the confusion.

As a general rule, selling your own used belongings is not taxable. Old clothes, a phone you upgraded, furniture you don’t want anymore. GOV.UK is explicit about this: items that belonged to you for your own use are personal possessions, and you probably don’t pay Income Tax on them. You could clear out 200 things from your wardrobe for £5,000 and owe nothing, with nothing to register. You’re selling your own property, usually for less than you paid for it.

It becomes a business when you buy or make things specifically to sell them at a profit, or you flip items regularly with a profit motive. That’s trading, and HMRC weighs it through what it calls the badges of trade. That’s when registration comes into it.

The line isn’t the platform. It isn’t the number of items either. It’s your intent and your pattern.

Probably not taxable	Probably a business
Clearing out your old wardrobe	Buying clothes to resell at a markup
Selling a phone you upgraded from	Flipping phones you source to sell
Selling furniture you no longer want	Making candles or prints to sell
One-off declutter, even a big one	Regular sourcing with a profit motive

If you’re on the left, the HMRC pop-up changes nothing for you. Hand over your NI number if asked, and carry on. There’s nothing to file.

When you do have to register

If you’re actually trading, the number to watch is the £1,000 trading allowance.

You can earn up to £1,000 of gross trading income in a tax year without telling HMRC. Go over £1,000 and you have to register for Self Assessment as a sole trader and file a return.

A few things people get wrong here:

It’s gross, not profit. The £1,000 is your income before expenses. If your sales come to £1,200 but you barely made a margin, you still have to tell HMRC, because the £1,200 is what counts.

It’s one allowance, not one per app. You don’t get a fresh £1,000 on each platform. It’s a single combined allowance across all your trading and casual income.

You choose the allowance or real expenses. You can either claim the flat £1,000 and deduct nothing, or deduct your actual costs. Whichever is better. If your real costs are well over £1,000, deducting actuals usually wins, but then you can’t also use the allowance.

The deadline is 5 October. If you went over £1,000 in a tax year, you register with HMRC by 5 October after that tax year ends.

Watch the two different calendars

This one trips people up. The two numbers run on different clocks.

Platform reporting runs on the calendar year, to 31 December. Your tax and the £1,000 allowance run on the UK tax year, 6 April to 5 April. They don’t line up, so don’t assume a figure from your eBay report maps straight onto your Self Assessment.

A quick word on the £6,000 thing

Capital Gains Tax is separate from all of this. Selling a single personal possession for more than £6,000 can trigger CGT, whether you’re trading or not. Most second-hand clothes and small items are nowhere near that, and many are exempt anyway as wasting assets. So for a normal wardrobe clear-out, this isn’t your problem. Worth knowing it exists though.

So, what should you actually do?

Place yourself first.

Selling your own used things? Even a lot of them? You’re fine. Give the platform your NI number if it asks, and don’t lose sleep over the report.

Buying or making things to sell at a profit? Then you’re running a small business. Track your gross income across every platform, and if it crosses £1,000 in a tax year, register by 5 October.

The honest summary: a report to HMRC is not a tax bill. The thing that decides whether you owe anything is whether you’re trading, not whether a pop-up appeared.

And if you do cross into business territory, that’s where keeping your income and your tax reserve separate stops being optional. It helps to have a sense of how much to set aside for tax before the bill lands. Knowing what you’ve earned isn’t the same as knowing what’s actually yours to keep. Nett works out that second number for you.