Whether it’s tutoring two evenings a week, a few VA clients or an Etsy shop, money you earn from home is usually taxable. Side income tax sounds scarier than it is. Small amounts often have simple rules, and in some cases you won’t owe anything at all. This guide explains how it works in Ireland, the UK and the US, with real examples.
Want your answer in 30 seconds? Use our side income tax checker. Pick your country, enter what you earn, and it tells you what to do and by when.
First: is it a business or just selling your old stuff?
Selling your own used things now and then (the buggy, outgrown clothes, the old sofa) is normally not a business, so it’s not taxable income. It becomes trading when you:
- Buy things to resell at a profit
- Make things to sell, like crafts, candles or printables
- Sell a service: tutoring, VA work, bookkeeping, pet-sitting, social media help
Online marketplaces in the EU and UK now report sellers with 30 or more sales, or about €2,000 a year, to the tax authority. That doesn’t mean you owe tax; it means the tax office can see your sales, so it pays to keep records.
Side income tax in Ireland
The rules depend on whether you also have a PAYE job.
- You have a PAYE job: if your side profit is €5,000 or less and your gross side income is €30,000 or less, you can usually declare it through Revenue myAccount on a Form 12. Revenue then collects the tax by adjusting your tax credits, so it comes out of your wages.
- Above those amounts: you become a “chargeable person”. You register for self-assessment and file a Form 11 on ROS by the Pay & File deadline (31 October the following year, extended to mid-November if you file and pay online).
- No PAYE job at all: any business income goes through self-assessment (Form 11), however small. You may still owe little or no income tax, because your personal and earned income tax credits cancel out the tax on a good part of your profit.
PRSI Class S applies once your self-employed income reaches €5,000 a year. That’s not all bad news: it builds your own social insurance record, which counts towards your State pension and some benefits. USC applies once your total income is over €13,000.
Example: Aoife has a part-time PAYE job and earns €2,400 a year tutoring, with €200 of costs. Her profit is €2,200, well under €5,000, so she declares it in myAccount on a Form 12. Revenue adjusts her tax credits for the next year.
Watch out: if you’re married and your household gets the Home Carer Tax Credit, earnings over €7,200 start to reduce it. Our childcare vs. work calculator includes this.
Side income tax in the UK
The trading allowance is your friend. In the 2026/27 tax year you can earn up to £1,000 of gross trading income without paying tax on it or telling HMRC. From 6 April 2027 it triples to £3,000.
- Under the allowance: no tax and no Self Assessment needed for that income. Keep simple records anyway.
- Over the allowance: register for Self Assessment by 5 October after the tax year ends, then file your return and pay by 31 January. For 2026/27 income that means registering by 5 October 2027 and paying by 31 January 2028.
- Allowance or real costs: you deduct either the trading allowance or your actual business costs, whichever is bigger, not both.
The allowance is for all your side income combined, not £1,000 per activity. If this is your only income, your Personal Allowance (£12,570) also applies, so you may owe little or no tax, but you still have to register once you’re over the trading allowance.
Example: Sam earns £2,400 from a craft shop in 2026/27, with £300 of costs. That’s over £1,000, so Sam registers for Self Assessment. Deducting the £1,000 allowance (bigger than £300 of costs) leaves £1,400 of taxable profit. In 2027/28, the same £2,400 would fall inside the new £3,000 allowance.
Side income tax in the US
The key number is $400. If your net profit from self-employment is $400 or more in a year, you must file a federal return and pay self-employment tax of 15.3% on 92.35% of your profit, on top of any income tax.
- 1099-NEC: from 2026, clients only send one once they pay you $2,000 or more in a year (it was $600).
- 1099-K: payment apps and marketplaces only send one above $20,000 and 200 transactions.
- No form doesn’t mean no tax. All income is taxable whether or not you get a 1099.
- Quarterly payments: if you expect to owe $1,000 or more, pay estimated tax each quarter (Form 1040-ES), or increase withholding at a W-2 job.
Example: Maria earns $3,000 as a part-time VA with $300 of costs. Her $2,700 profit is over $400, so she files Schedule C and Schedule SE. Her self-employment tax is about $381, and half of it is deductible.
Simple habits that make side income tax easier
- Open a separate bank account for side income, even a free one.
- Photograph receipts for software, materials, platform fees and equipment.
- Set aside 20–30% of your profit until you know your real tax bill.
- Put the deadlines for your country in your calendar now.
- If you’re unsure, check the official guidance on Revenue.ie, GOV.UK or IRS.gov, or ask a tax adviser.
Behind on side income tax? What to do
Don’t panic, and don’t ignore it. Contact the tax office as soon as possible. Coming forward voluntarily nearly always means lower penalties than being found later.
Rules checked November 2026, including the UK trading allowance increase from 6 April 2027 and the US 1099 threshold changes from 2026. This is general information, not tax advice.
Find out when you need to declare what you earn from home.
