Side Hustle Tax in the UK: When You Need to Tell HMRC (And When You Don't)

The question comes up constantly: I earn a bit on the side — selling on Etsy, doing the odd bit of freelance work, driving for a delivery app on weekends. Do I need to tell HMRC? And if so, when exactly?

The honest answer is that it depends on how much you earn and what type of income it is — but the rules are clearer than most people assume. This guide walks through exactly when side income triggers a tax obligation, how the £1,000 trading allowance works, and what the rules mean practically for the most common side hustles.

The £1,000 trading allowance

The trading allowance is a relief that lets you earn up to £1,000 from self-employment or trading income each tax year without paying any tax on it and without needing to register for Self Assessment. It was introduced specifically to cover small, informal trading activity — selling homemade goods, casual freelance work, occasional gig economy earnings, and so on.

The key things to understand:

It's per person, per year. Each individual gets £1,000. It doesn't apply per source of income, so if you have two side gigs earning £700 each, your total trading income is £1,400 — over the threshold.

It covers gross income, not profit. Unlike the income tax system (which taxes profits after expenses), the trading allowance applies to your total receipts before any costs. Earn £950 in total, and you're covered regardless of your expenses. Earn £1,100, and you've exceeded it — but you can then choose whether to use the allowance or deduct actual expenses, whichever gives you a lower taxable figure.

It doesn't apply to employment income. Income taxed through PAYE — your regular salary — is handled separately and doesn't interact with the trading allowance.

Property income has a separate £1,000 allowance. If you rent a room informally or have a small amount of rental income, that's covered by the property allowance, not the trading allowance.

The Trading Allowance Calculator lets you compare using the allowance against deducting actual expenses, which is worth doing if your costs are high.

When you must register with HMRC

The £1,000 allowance means you don't need to register or file a return if your total self-employment income stays below that figure. Once you exceed £1,000, you need to register for Self Assessment and declare the income — even if no tax ends up being due.

The registration deadline is 5 October following the end of the tax year in which you exceeded the threshold. So if you earned £1,200 from a side hustle during the 2026/27 tax year (which ends 5 April 2027), you need to register by 5 October 2027.

There's a common misconception that you only need to register if you'll actually owe tax. That's not quite right — the legal obligation is based on whether your income exceeds the relevant threshold, not whether you end up with a tax bill. Failing to register when required can result in penalties, even if no tax was owed.

That said, HMRC uses a level of discretion with genuinely small amounts, and the chance of facing penalties on £1,100 of income declared a month late is low in practice. But the principle is clear: once you're over £1,000, register.

How side income stacks on your main salary

This is the part many people miss. Your self-employed profit is added to your other income for income tax purposes. Your Personal Allowance (£12,570) and tax bands are applied to your total income, not to each source separately.

This means:

If you earn £45,000 in your day job and £8,000 from a side hustle, your total income is £53,000. Your side hustle income is effectively taxed at 40% (the higher rate) because your day job has already filled the basic rate band up to £50,270.
If you earn £30,000 employed and £6,000 self-employed, your total is £36,000. All of the side hustle profit falls in the basic rate band, so it's taxed at 20% (plus Class 4 NIC at 6% on the profit above £12,570).

For anyone with a salary that already puts them into or near the higher rate band, this matters quite a lot. A £10,000 side hustle might feel like a useful income boost, but after 40% income tax and Class 4 NIC (even at 2% above the upper profits limit), the net might be closer to £5,800.

The Income Tax Calculator and Self Assessment Estimator can model this for you — just make sure to include both income sources.

Common side hustles — what the tax rules mean in practice

Selling on eBay, Vinted, or Etsy

Occasional personal selling — clearing out old clothes, selling things you no longer need — is not trading and is not taxable. HMRC distinguishes between personal sales and trading activity.

Trading activity is characterised by: buying to resell, making items to sell, selling regularly and repeatedly, or making a profit in a business-like way. If you're buying bundles at car boot sales and reselling them on eBay for profit, that's trading. If you're selling your old coat, that's not.

If you're genuinely trading on these platforms, your total receipts (minus costs of goods sold and any other allowable expenses) is your profit, and the £1,000 trading allowance applies if you're under that amount.

Freelance work (writing, design, development, consulting)

Freelance income is straightforwardly self-employment income. If you earn over £1,000 in a tax year from freelance work — even from a single invoice — you need to register for Self Assessment. You can deduct legitimate business expenses (software, home office costs, professional subscriptions) before calculating profit.

If you're employed full-time and doing occasional freelance work, the most common scenario is that your employer hasn't left much room in the basic rate band, so your freelance profit is likely to face 40% income tax. This is worth modelling before you quote day rates.

Driving for Uber, Deliveroo, or similar

Platform work through gig economy apps is self-employment, not employment (despite various legal disputes — HMRC treats it as self-employment for tax purposes). You're responsible for declaring and paying your own tax on earnings.

Vehicle costs are a significant deduction. You can either track actual costs (fuel, servicing, insurance, depreciation) and apportion the business fraction, or use HMRC's mileage rate — 45p per mile for the first 10,000 business miles, 25p after. For most drivers, the mileage rate is simpler and often comparable.

Class 4 NIC applies to net profit above £12,570, and Class 2 NIC is treated as paid automatically if your profits are at that level. If earnings fluctuate, some years you may be above the threshold and some below — keep records carefully.

Content creation: YouTube, TikTok, Twitch, podcasting

Ad revenue, sponsorships, affiliate income, and platform payouts all count as self-employment income. If your total in a year exceeds £1,000, register and declare.

Content creation expenses can be broad: equipment, software, subscriptions to services you review, a proportion of broadband costs, a home office allowance. HMRC expects you to be able to justify each claim, so keep receipts and document the business rationale for anything that could look personal.

For creators who also have a day job: your ad revenue and sponsorship income stacks on top of your salary just like any other self-employment income.

Renting out a room or property

Rental income has its own £1,000 property allowance — separate from the trading allowance. If you rent out a room in your home and earn less than £1,000, you don't need to declare it. Above that, you choose between using the allowance or deducting actual expenses.

The Rent a Room scheme allows up to £7,500/year tax-free if you let a furnished room in your main home and live there too. This is a more generous relief that applies specifically to residential letting in your own home.

What expenses can you claim?

If your side hustle income exceeds £1,000 and you opt not to use the trading allowance (because your actual expenses are higher), you can deduct:

Cost of goods sold (if you buy to resell)
Packaging, postage, and platform fees
A proportion of home costs if you work from home
Business mileage at the HMRC-approved rate
Equipment and software used for the business
Professional development directly relevant to the work

You can't deduct costs that are personal in nature, your own time, or capital costs (though you may be able to claim capital allowances on equipment).

What happens if you don't register?

HMRC receives data from many of the platforms people use — payment processors, digital marketplaces, gig economy apps, and property rental platforms increasingly report income to HMRC. The idea that cash or online platform income is invisible is increasingly wrong.

Penalties for late registration start at a flat £100, increasing based on how long the delay lasts and how much tax was owed. HMRC can also charge interest on late payments. In serious cases of deliberate non-compliance, penalties can reach a significant percentage of the tax owed.

The risk isn't worth it. If you're over £1,000, register. It takes about 20 minutes online and the process is straightforward.

The simple summary

Under £1,000 in total self-employment income? No obligation to register or declare.
Over £1,000? Register by 5 October after the tax year ends.
Your side hustle profit stacks on top of your salary for income tax purposes — model the combined picture before setting rates.
The trading allowance (£1,000) is simpler to use; actual expenses are worth calculating if your costs are significant.
Most gig economy and platform income is treated as self-employment regardless of how the platform describes your status.

Use the Trading Allowance Calculator to compare the allowance against deducting actual expenses, and the Self Assessment Estimator to estimate your combined tax bill before January.