Use this free side income tax checker to see whether you need to declare money you earn from home in Ireland, the UK or the US, and how to do it. The side income tax checker runs in your browser, and our side income tax guide explains the rules in more detail.

General information for planning, not tax advice. Runs in your browser; nothing is stored or sent.

Do you need to declare side income?

Earning a little from home – tutoring, VA work, selling crafts – raises the same question in every country: do I have to tell the tax office? The honest answer is that almost all business income is taxable, but small amounts often have simple ways to declare them, and sometimes no tax at all. This side income tax checker gives you the rule that applies to you in Ireland, the UK or the US, and the deadlines to put in your diary.

Side income tax checker: the rules in short

Ireland

If you have a PAYE job and your side profit is €5,000 or less (with gross side income of €30,000 or less), you can usually declare it through Revenue myAccount on a Form 12, and Revenue collects the tax through your wages. Above those amounts, or if you have no PAYE income at all, you register for self-assessment and file a Form 11. Having no job doesn’t mean you’ll owe a lot: your personal and earned income tax credits cover a good chunk of profit. PRSI Class S applies once self-employed income reaches €5,000, which also counts towards your State pension.

UK

The trading allowance lets you earn up to £1,000 of gross trading income a year without tax or a tax return (2026/27). From 6 April 2027 it triples to £3,000. Go over it and you register for Self Assessment by 5 October after the tax year ends, then file and pay by 31 January. You can deduct either the allowance or your real costs, whichever is bigger.

US

Once your net profit from self-employment reaches $400 in a year, you must file a return and pay self-employment tax (15.3% on 92.35% of profit), on top of income tax. From 2026, clients only send a Form 1099-NEC once they pay you $2,000 or more, and payment apps send a 1099-K only above $20,000 and 200 transactions. None of that changes what you owe: income is taxable whether or not a form arrives.

Selling your old stuff isn’t the same as a business

Clearing out the kids’ outgrown clothes on Vinted is usually not trading, so it’s not taxable income. It becomes a business when you buy things to resell or make things to sell. Online marketplaces in the EU and UK now share seller data with tax authorities once you make 30 or more sales or about €2,000 a year, and that’s a good reason to keep records.

Keep it simple from day one

Open a separate bank account (even a free one) for side income.
Save receipts for software, materials and fees – photos on your phone are fine.
Set aside 20–30% of profit for tax until you know your real figure.
Check the official guidance: Revenue.ie, GOV.UK or IRS.gov.

Side income tax checker FAQs

I only earn a few hundred a year. Do I really need to declare it?

In the UK, not if your gross trading income is within the £1,000 trading allowance (£3,000 from April 2027). In the US, you don’t owe self-employment tax under $400 of profit, but income is still reportable. In Ireland, all income is taxable; with a PAYE job, small amounts are declared simply through myAccount.

Will I lose benefits or credits if I start earning?

Possibly. In Ireland, earnings over €7,200 start to reduce the Home Carer Tax Credit your household gets. In the UK, Universal Credit counts self-employed earnings. Use our childcare vs. work calculator to see the full picture.

Can the tax office see my Etsy, eBay or PayPal income?

Yes, increasingly. EU and UK platforms report sellers with 30+ sales or about €2,000 a year, and US platforms send 1099-K forms above $20,000 and 200 transactions. It’s always safer to declare correctly.

What if I missed a deadline?

Contact the tax office as soon as you can. Coming forward voluntarily almost always leads to lower penalties than being found later.