Side Hustle Tax in the UK 2026/27: When You Need to Tell HMRC

The £1,000 Trading Allowance: Your Starting Point

Every individual in the UK gets a trading allowance of £1,000 per tax year, covering income from self-employment, casual work, or trading-type activity. If your gross side income (before expenses) is £1,000 or less in a tax year, and this is your only self-employment income:

• You don't need to register for Self Assessment for this income
• You don't need to declare it
• No tax is due on it

This is separate from — and in addition to — your Personal Allowance (£12,570 for 2026/27), which covers employment and other income.

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When You Cross the £1,000 Threshold

Once gross side income exceeds £1,000 in a tax year, you must register for Self Assessment (by 5 October following the end of the tax year in which you started) and declare the full amount, even the first £1,000. You then choose between two ways to calculate the taxable profit:

You pick whichever produces the lower taxable profit each year — if your real expenses are under £1,000, the flat allowance is usually more generous; if they're higher, claiming actual expenses saves more tax.

Example: £4,000 gross income from freelance design work, £600 of actual expenses (software subscriptions, a proportion of home broadband).

Here, the trading allowance produces a lower taxable profit (£3,000 vs £3,400) and would normally be the better choice.

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What Counts as Taxable "Side Hustle" Income

The key legal test for whether an activity is "trading" considers factors including frequency, intention to profit, and whether items were acquired specifically for resale — HMRC's "badges of trade" test. A single clear-out sale is very different from a regular pattern of sourcing and reselling goods.

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Digital Platform Reporting: What Changed

Since January 2024, digital platforms operating in the UK — including Vinted, eBay, Airbnb, Etsy, Deliveroo, Uber and similar — must collect seller/earner information and report it annually to HMRC, once an individual crosses reporting thresholds (broadly, more than around 30 sales transactions or income over roughly €2,000-equivalent in a calendar year), under international OECD tax transparency rules.

This does not create any new tax that wasn't already owed — the underlying rules on what's taxable haven't changed. What has changed is that HMRC now automatically receives data it previously had to request individually, making it far more straightforward for HMRC to cross-reference against Self Assessment records and flag gaps.

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Worked Example: A Weekend Freelancer

Priya has a full-time PAYE job and does freelance graphic design at weekends, earning £3,500 gross in the 2025/26 tax year, with £400 of allowable expenses.

Priya needs to register for Self Assessment by 5 October following the tax year she first exceeded £1,000, then file her return by 31 January, declaring both her side income and her employment income (which HMRC already knows about via PAYE, but it still needs including on the return for the full picture).

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Practical Steps If You're Not Sure Where You Stand

1. Add up gross side income for the tax year (6 April to 5 April) — if under £1,000, no action needed for that income specifically.
2. If over £1,000, register for Self Assessment as soon as reasonably possible — the 5 October deadline (following the tax year end) applies, but registering earlier avoids a last-minute scramble.
3. Keep basic records — dates, amounts, what the income was for, and receipts for any expenses you might want to claim, from day one rather than trying to reconstruct them later.
4. If you've under-declared in previous years, consider HMRC's digital disclosure service to come forward voluntarily — penalties are significantly lower for unprompted disclosure than for HMRC discovering it first.