Selling on a marketplace, DJing at weekends, walking dogs, renting out a drill, doing a bit of freelance design. A great many people earn a little on the side, and most assume it is too small to bother HMRC. Sometimes that is true. Often it is not, and the line sits where people expect it least.

The rule that decides it is the £1,000 trading allowance. It is generous, and it keeps trivial income out of the system. It is also misunderstood in two specific ways that catch people out: it is a single combined allowance across everything you do, and it is measured on gross income, before a penny of expenses comes off.

This guide sets out how the allowance works, how it differs from the property allowance, when a side hustle tips you into Self Assessment, and the two dates you cannot miss.

• The trading allowance is £1,000 per tax year, combined across all your trading and casual income, not one allowance per activity.
• The test is on gross income, which gov.uk defines as "the total amount you would put on your tax return before any allowances or expenses are taken off".
• The property allowance is a separate £1,000 for income from land or property, and you can use both allowances in the same year.
• Gross trading income above £1,000 generally means registering for Self Assessment by 5 October following the tax year, then filing and paying by 31 January.
• Above £1,000 you may deduct either the allowance or your actual expenses, whichever is better, but never both.

The trading allowance is a tax exemption designed to keep small amounts of casual income out of the tax system entirely.

The £1,000 is one allowance covering all your trading, casual and miscellaneous income together. Sell crafts online and also do occasional gardening for cash, and you do not get £1,000 for each. You add them together and compare the total against the single allowance. This is the detail that trips people up most, because treating each hustle separately feels natural.

⚠️ Watch: The £1,000 test applies to gross income. HMRC's guidance is explicit: gross income is "the total amount you would put on your tax return before any allowances or expenses are taken off". Turn over £1,400 and spend £600 on materials, and you are over the threshold even though your profit is £800.

This is where confident, wrong answers cluster. A profit-based reading of the rule feels intuitive and produces the wrong conclusion for anyone with real costs.

If your gross trading income for the tax year is £1,000 or less, the allowance generally gives full relief. You usually do not need to tell HMRC about it or file a return on account of that income, provided you have no other reason to file.

Above £1,000 you have a choice. Deduct the £1,000 allowance instead of your actual expenses, which is simpler and usually better for low-cost activities. Or, where real expenses exceed £1,000, deduct those and do not use the allowance. Take whichever produces the lower taxable profit. You cannot use both.

The choice carries one consequence worth spelling out. Claiming the allowance replaces your expenses altogether, so a loss-making year cannot produce a loss to carry forward or set against other income. Where costs exceed income, deducting actual expenses is usually the better route even though it means more record-keeping.

The two allowances look identical and are frequently confused, but they cover different income and stand separately.

The trading allowance covers self-employment and casual services. The property allowance covers income from land or property, such as renting out a parking space, a driveway or a patch of land for storage. Each is £1,000, and gov.uk is clear that "if you have both types of income, you'll get a £1,000 allowance for each".

📌 Key point: The property allowance cannot be used on income from letting a room in your own home under the Rent a Room Scheme. Rent a Room is its own relief, worth up to £7,500 a year, halved to £3,750 where the income is shared with someone else.

Mixing these two up is the most common error in this area, because both sound like "small property income" to a non-specialist.

You cannot combine the two into a £2,000 pot against one type of income. The trading allowance shelters trading income; the property allowance shelters property income. Keeping the two streams separate in your records makes this straightforward.

The exclusions are short and precise. You cannot use the allowances on income from:

• a company you or someone connected to you owns or controls;
• a partnership where you or someone connected to you are partners;
• your employer, or the employer of your spouse or civil partner.

The purpose is to stop people converting employment or company income into "casual" income that a £1,000 allowance would shelter.

Crossing £1,000 of gross trading income is the usual trigger, but it is worth being precise about what counts as trading and what to do next.

Selling personal belongings you no longer want is generally not trading, and one-off casual sales usually are not either. Buying or making things to sell, providing services for payment, or acting with regularity and a profit motive looks like trading. Only trading income counts towards the allowance and the filing trigger.

Where your gross trading income for the year exceeds £1,000, you must register for Self Assessment. For income earned in the 2025 to 2026 tax year, the deadline to register is 5 October 2026. Registering late can attract penalties, so the date matters even though the return itself is due later.

Once registered, you file the return and pay any tax due by 31 January 2027 for the 2025 to 2026 year.

Online platforms now pass seller information to HMRC once a year, reporting a calendar year's data by the following 31 January. Broadly, sellers below a small-scale threshold, meaning fewer than 30 sales of goods and under about £1,700 (€2,000) in the calendar year, are not reported.

A letter or an on-platform notice unsettles people, so the position is worth stating plainly: being reported does not by itself mean tax is owed. HMRC's own guidance says so. What creates a liability is trading or making a capital gain, which is why the trading test above matters more than the report.

"Two dates and one word: gross. Get those right and the rest of this rule looks after itself."

The government has announced that the Self Assessment reporting threshold for trading income will rise from £1,000 to £3,000 of gross income, with a simplified online service for people who fall between the two figures.

⚠️ Not yet in force. No start date has been set. The change is expected before the end of the current parliament, which allows until 2029. Until it takes effect, the £1,000 threshold and the dates above continue to apply.

One point is routinely misreported and worth stating plainly: this raises the threshold for filing a return, not the tax-free allowance. Income between £1,000 and £3,000 remains taxable; it would simply be reported and paid through a simpler route rather than a full return.

Side-hustle questions are high-volume and deceptively fiddly, which makes them a good test of any research tool.

Four things decide most of these cases: whether the allowance is combined or per-activity, whether the test is gross or profit, whether the activity is genuinely trading, and the two deadlines. An answer that gets the gross point wrong, or quotes the wrong dates, is not a small error. It can mean a missed registration and a penalty.

Because these rules are simple to state and easy to misremember, this is the kind of question where confirming from a source beats relying on memory. GAIN Tax returns the answer with the relevant gov.uk guidance pinned to it, so you confirm the position rather than recall it, and our sources and update policy sets out how that guidance is kept current, which matters on a threshold that is due to move. For the broader question of choosing a tool you can trust on volume questions like these, see our guide to choosing AI tax research software, and our published accuracy benchmark.

The £1,000 trading allowance is a friendly rule with two sharp edges: it is combined across all your side hustles, and it is measured on gross income before expenses. Add up everything you earn from trading and casual work in the year, compare the gross total against a single £1,000, and if you are over it, register by 5 October and file and pay by 31 January.

For most people with a modest side income, that is the whole story. For anyone advising them, the value sits in getting the combined-allowance point, the gross test and the two dates right every time.

This guide covers income tax and the filing trigger. National Insurance can also arise on self-employed profits and follows its own thresholds and rules, so treat it as a separate check rather than an afterthought.

To check a real side-hustle question with the guidance attached, start a free GAIN Tax trial, or book a call. More guides are on the GAIN Tax blog.

Is the £1,000 trading allowance per side hustle or combined? It is a single combined allowance across all your trading and casual income for the tax year, not one per activity. Add all your trading income together and compare the total against the single £1,000.

Is the £1,000 measured on profit or on turnover? On gross income. HMRC defines gross income as the total you would put on your tax return before any allowances or expenses are taken off, so £1,400 of takings with £600 of costs is over the threshold even though the profit is £800.

Do I have a separate allowance for property income? Yes. The property allowance is a separate £1,000 for income from land or property, and you can use both allowances in the same tax year. You cannot merge them into a single larger allowance.

Can I use the property allowance for renting out a room in my home? No. Income from letting a room in your own home falls under the Rent a Room Scheme, which is a separate relief worth up to £7,500 a year, halved to £3,750 where the income is shared.

When do I need to register for Self Assessment for a side hustle? Where your gross trading income for the year exceeds £1,000. For 2025 to 2026 income, the deadline to register is 5 October 2026, with the return filed and tax paid by 31 January 2027.

Is the threshold really going up to £3,000? The government has announced a rise in the Self Assessment reporting threshold to £3,000 of gross trading income, with a simplified service for those in between, but no start date has been set and it is expected before the end of this parliament. It raises the filing threshold, not the tax-free allowance.