Side hustle tax in the UK: when you actually owe (and how much)

Side hustle tax sounds scarier than it is. For most people starting out the rules are simple and the bill is small.

Here’s the calm version, with the numbers.

Checked against GOV.UK on 20 July 2026. Figures are for the 2026/27 tax year; sources at the end.

The magic number: £1,000

You can earn up to £1,000 a year from self-employment or casual trading without needing to register or pay tax on it. This is the trading allowance. Under it, HMRC essentially leaves you alone.

Go over £1,000 in a tax year and you generally need to register for Self Assessment and declare the income.

Three things about that £1,000 trip people up:

It’s gross income, not profit. Sell £3,000 of stock that cost you £1,800 and your profit is £1,200, but your income is £3,000, so you’re over. The allowance is measured before expenses.

It’s a tax year, not a calendar year. 6 April to 5 April.

It’s across everything, not per platform or per hustle. £600 of Vinted sales plus £700 of freelance design is £1,300 of trading income. Over.

You may also have seen that the threshold is rising to £3,000. That is not in force. £1,000 is what applies today.

Income versus profit

If you cross the threshold, you’re taxed on profit, not on total sales. This is the difference between a scary number and a real one.

Sell £3,000 of stock that cost you £1,800, with £240 of platform fees and £160 of postage, and your profit is £800, not £3,000. You declare the £3,000 and claim £2,200 of costs.

Which is why tracking what you spend matters as much as tracking what you earn. Costs you can’t evidence are profit you get taxed on but never had.

Trading versus clearing out

There’s a real difference between selling your own used things and running a hustle, and it decides whether any of this applies at all.

Selling personal items you no longer want (old clothes, an unused gadget, furniture from a house move) is generally not taxable. You’re decluttering, not trading, and it doesn’t matter how much it adds up to.
Buying to sell, or making to sell, for profit is trading, and the £1,000 allowance and tax rules apply.

The test is why you acquired the thing. Bought to use and later sold points away from trading. Bought specifically to sell points firmly towards it.

See do you pay tax on Vinted and eBay sales for how this plays out on the marketplaces, including the platform reporting rules.

The part nobody explains: your personal allowance is probably already spent

This is where side hustles differ from a full-time business, and where people get the biggest shock.

If you have a job, your £12,570 personal allowance is already being used by your salary. It doesn’t reset for the side hustle. So side hustle profit generally gets taxed at your marginal rate, the rate on the next pound you earn, from the very first pound of profit.

If you’re a basic rate taxpayer that’s 20% Income Tax plus 6% Class 4 National Insurance, so 26% on side hustle profit.

If your salary already puts you over £50,270, it’s 40% plus 2%, so 42%.

A side hustle making £3,000 profit alongside a £35,000 job therefore costs around £780 in tax, not nothing. People who mentally applied a fresh personal allowance to the side hustle get an unpleasant surprise in January.

The rule of thumb: set aside a third of side hustle profit if you’re a basic rate taxpayer, and closer to a half if your job puts you in the higher band. Better to over-save and get a pleasant surprise.

A worked example

You have a £35,000 job and made £4,000 profit reselling.

Your salary uses the personal allowance and sits in the basic rate band
The £4,000 of profit is taxed at 20% = £800
Class 4 National Insurance at 6% = £240
Total: roughly £1,040

The job’s tax carries on through PAYE as normal. The £1,040 is what you owe through Self Assessment, due by 31 January.

Watch for payments on account

If your Self Assessment bill reaches £1,000 or more, and less than 80% of your tax was collected at source, HMRC asks you to pay towards next year in advance. Two instalments, on 31 January and 31 July, each usually half of last year’s bill.

For side hustlers this creeps up. A lot of your tax is collected at source through PAYE on the job, which often keeps you out of payments on account early on. But as the hustle grows the bill crosses £1,000, and suddenly the January payment is around 150% of what you calculated.

Not a penalty, not extra tax, just earlier. Worth seeing coming.

What to do about it

Keep a running total of income and costs from day one, not from when you cross £1,000. You can’t reconstruct costs later, and unrecorded costs are tax you didn’t need to pay.
Watch the £1,000, on gross income, across everything combined.
Register for Self Assessment by 5 October following the end of the tax year you crossed in. Register early, because the UTR arrives by post and you can’t file without it.
Set aside a third of profit as you earn, more if you’re a higher rate taxpayer.
Keep receipts for at least five years after the January filing deadline.
Claim your pre-trading costs. Things you bought before you started can generally be claimed as if incurred on day one.

One thing to check if you have a job

Look at your employment contract. Some have clauses about outside work, secondary employment or conflicts of interest.

This isn’t a tax question and HMRC doesn’t care, but it’s worth knowing where you stand before the hustle gets big enough to notice. Most clauses are about direct competition and using company time or equipment, not about you selling on Vinted at the weekend.

It’s painless if the numbers are already there

The people who find side hustle tax stressful are the ones trying to work out in January what they earned and spent across a year and three platforms.

Sedonis tracks income, costs and profit as you go, so when you cross the line you’re ready rather than scrambling. Free to start.

Next steps

Do you pay tax on Vinted and eBay sales? · the marketplace rules in detail
How to register as self-employed
What you can claim as a sole trader
Self-employed tax calculator
How to start a business in the UK · the full nine-step guide

Checked against GOV.UK on 20 July 2026: tax-free allowances on trading income, Income Tax rates, self-employed National Insurance, payments on account, Self Assessment deadlines. Rules and allowances change, usually each April.

General information, not tax advice. Your marginal rate depends on your total income from all sources. Check GOV.UK or an accountant for your situation.