How HMRC Knows About Your Side Hustle Income in 2026

If you sell online or earn money through an app, you may have heard that HMRC can now see your income. It is true, and this post explains exactly how, what data is shared, what it means for you, and what to do if you are worried you have not declared something you should have.

The Rule That Changed

From January 2024, the UK adopted international rules requiring online platforms to report seller data directly to HMRC once a year. The first reports covered the 2024 calendar year and were submitted in January 2025. The same cycle repeats annually, so platform data for 2025 was reported in January 2026, and the pattern continues each year after that.

It is worth being clear about what this was and what it was not. This was not a new tax, and it did not change a single rule about when you owe tax or how much. The thresholds, the trading allowance and the tax rates are all exactly the same as they were before. What changed is purely that HMRC now receives the data directly from the platforms, which means it can see online selling activity that it previously had no easy way to check. The rules about what you owe have not moved. The visibility HMRC has over them has.

Which Platforms Report

The rules apply to a wide range of digital platforms, including the ones most side hustlers use day to day.

Selling platforms such as Vinted, eBay, Etsy and Depop report seller data. Accommodation platforms such as Airbnb report host data. Gig and service platforms such as Uber, Deliveroo and various freelance marketplaces report worker data. In broad terms, the rules cover platforms that facilitate the sale of goods, the provision of personal services, the rental of property, and the rental of transport.

If you earn money through a digital platform that connects you with customers or buyers, there is a good chance it falls under these rules. The platforms themselves collect and submit the data, so this happens automatically in the background whether or not you are aware of it.

What Triggers a Report

A platform must report your data to HMRC if you cross either of two thresholds in a calendar year.

The first is completing 30 or more sales or transactions in the year. The second is earning roughly £1,700 or more in total sales. The £1,700 figure comes from a euro-denominated amount set in the international rules, so the exact sterling figure shifts slightly with exchange rates, but £1,700 is the working number to keep in mind.

If you cross either threshold, the platform reports your data. If you stay below both, the platform does not report you, although you are still subject to the normal tax rules regardless. Staying under the reporting thresholds does not mean you are under the tax threshold, which is a separate and lower figure we come back to shortly.

What Data Is Shared

When a platform reports you, it does not simply send a single total sales figure. It shares your name, your address, your date of birth, your National Insurance number or other tax reference where the platform holds it, and your transaction details including the number of sales and the gross amount you received. HMRC receives enough information to identify you precisely and to see the scale of your selling activity across the year.

The platform is also required to give you a copy of the data it sends to HMRC, usually through your seller dashboard or by email. If you think you may have crossed a reporting threshold, it is worth logging in and checking for this, so you know exactly what HMRC has received about you.

The Reporting Threshold Is Not the Tax Threshold

This is the single point that causes the most confusion, so it is worth being completely clear about it.

The reporting threshold of 30 sales or £1,700 is simply the point at which the platform shares your data with HMRC. It is not the point at which you start owing tax. The actual tax threshold is the £1,000 trading allowance, which is lower and measured differently, based on your gross trading income rather than the number of transactions.

The two figures do completely different jobs. The reporting threshold decides whether the platform sends your details to HMRC. The trading allowance decides whether you owe tax. Because they are different, you can easily fall on different sides of each one. You can have your data reported to HMRC without owing any tax at all, for example if you are simply selling unwanted personal possessions and happen to cross the 30-sale mark while clearing out your home. The data being reported does not mean tax is due. It only means HMRC can now see the activity and check it against what you have declared.

The reporting rules, then, do not change what you owe by a single penny. They simply give HMRC the information to check whether what you have declared matches what you actually earned.

What This Means in Practice

For most casual sellers, nothing changes at all. If you are selling your own personal possessions, you owe no tax and have nothing to fear from your data being reported, even if you cross the 30-sale threshold by clearing out a wardrobe or a loft. Selling things you already owned is not trading, and it is not taxable.

If you are trading but your gross income is below the £1,000 trading allowance, you owe no tax and do not need to register, regardless of whether your data is reported.

If you are trading above £1,000 and have been declaring it correctly, the reporting rules simply confirm what you already report, and there is nothing further to do.

The people who genuinely need to act are those trading above £1,000 who have not been declaring it. For them, the reporting rules mean HMRC now has the data to spot the gap between what was earned and what was declared, and the sensible move is to put things right before HMRC makes contact. Our full guide to tax on online selling income explains exactly what to do, step by step, and our post on the badges of trade helps you work out whether your activity counts as trading in the first place, which is the question that decides everything else.

If You Receive a Nudge Letter

HMRC uses the platform data to send what it calls nudge letters. These go to people whose reported income suggests they may have tax to declare that has not appeared on a return. The letters reference the data the platform shared and invite you to check and confirm your position.

If you receive one, the worst thing you can do is ignore it. A nudge letter is an invitation to put things right, and responding promptly is far better than leaving it and risking a formal enquiry later. Check whether you actually needed to register and declare, work out your true position, and respond honestly. In many cases the tax owed turns out to be small, and coming forward voluntarily generally leads to a far better outcome than waiting to be chased.

If you are unsure how to respond, or worried about what you might owe for previous years, a Done With You session will go through your specific position, work out where you genuinely stand, and help you respond to HMRC correctly and calmly.

The Bottom Line

HMRC can now see your online selling activity in a way it could not before, but this does not change what you owe. If you are selling personal items or trading below £1,000, you have nothing to worry about. If you are trading above £1,000, the right move is simply to declare it properly, and the sooner the better if you have fallen behind.

If your online selling has crossed the £1,000 mark or is heading that way, the most useful thing you can do is start tracking your gross income properly so you always know exactly where you stand. The UK Online Seller Tax Template is built specifically for this. It tracks your gross sales before fees, separates personal item sales from trading income, and calculates your income tax, National Insurance, student loan and payment on account automatically using confirmed 2026/27 rates. It works in both Google Sheets and Excel, and there is no monthly subscription.

Get the UK Online Seller Tax Template, £14.99 →