This article was first published on Freelancing in Focus on LinkedIn.

The ‘side hustle’ has undoubtedly become one of the biggest workplace trends of the 2020s. Where the ‘great resignation’ and ‘quiet quitting’ eras have already faded into memory, side hustling is already a permanent fixture of our economy.

We hear a lot about how popular they are among our youngest workers – Gen Z – who range from ages 14 to 29 at the time of writing. A quick web search will tell you that more Gen Zs have a side hustle than don’t. It’s enough hype to give this writer, who doesn’t currently have a side gig, FOMO.

Rather than work on my own side hustle idea, I instead decided to send a Freedom of Information request to HMRC asking for age-breakdowns of recent tax returns, to see if my FOMO was justified. Here’s what I found.

We used official jobs statistics to estimate that, in 2025, 475,000 people in Britain had what we call a side hustle. If that sounds low to you, there’s a good reason why.

When IPSE talks about side hustles, we’re talking about people who are employed in their main job whilst earning a secondary self-employed income. Selling unwanted clothes or household items doesn’t meet that definition, for example. Having a second job similarly doesn’t meet that definition.

This isn’t to denigrate the resourcefulness and commitment that doing either of these things requires. But many online surveys and articles will bundle these activities in with self-employed side hustles, potentially giving the impression that side businesses are something most people have.

So, IPSE’s definition is about realistically capturing what most people tend to imagine a ‘side hustle’ involves – using your skills, passion and motivation to generate a side income without an employer.

No, it’s not all hype – but it is more measured than the LinkedIn-verse would have you believe.

Responding to a Freedom of Information request, HMRC gave us an age-breakdown of all tax returns they received for the 2023-24 tax year (the most recently available year). We then compared this against already available data for the 2020-21 tax year, when side hustling really began to have its moment. Here’s the comparison: 

(I will return to what’s happening with the over 65s later – but first, the under 25s.

It shows a modest but nonetheless significant increase in under 25s submitting tax returns in that three-year period. Three key things to note:

Younger workers less likely to own assets

Because younger workers are less likely to own assets that generate taxable income, such as property or dividends, it’s much more likely that their tax returns are being generated by self-employment income, including side hustles.

Full-time self-employment is less likely among younger workers

We previously estimated that there were c.162,000 under 25s in full time self-employment in 2024. Whilst we can’t directly compare the data, it points to there being a sizeable chunk of part-time self-employment in that age group – many of which will be side hustles.

Not all side hustles create a tax bill

However, the FOI data won’t capture any side hustlers who did not earn over the £1,000 Trading Allowance threshold, and therefore will not have reported their income to HMRC. There could be many who are holding their side hustle incomes below that threshold – a big part of the reason why we’re campaigning for the Trading Allowance to increase.

Read more about our campaign to raise the Trading Allowance and give side hustlers a bigger tax break.

Overall, the evidence points to an increase in self-employment and side hustling among younger workers. But whether it counts as a ‘revolution’ comes down to how you view it.

Whether it’s full time or part time, self-employment comes with risk, and no guarantee of income. It’s why self-employment tends to be more popular among older age groups, particularly people aged 50 and older, who have many years of professional experience to back themselves. This is something that, regardless of their talents, younger workers just don’t have. 

With this in mind, the steady rise in the number of under 25s taking on a side hustle really is extraordinary. But there are far fewer of them than headlines would have you believe.

Freelancing has long been a popular path for professionals in the latter stages of their careers. They may decide to leave full-time employment to take on freelance roles as consultants, non-executives and advisors. This way, they can wind down their careers before retirement. But has there really been a 12% increase?

It’s unlikely – using tax returns to measure self-employment is much harder in older age groups, as they are more likely to have accrued property, investment and dividend income sources that also require a tax return.

We think it’s best explained by a combination of factors. Increases in the value of property and dividend income, and even the state pension, will have pushed many more into having to file a tax return because of a freeze to the personal tax allowance threshold.