In short
To start a side business, check your employment contract for rules on outside work and conflicts of interest, choose an idea that fits your free time, register as required where you live, set aside money for taxes on your side income, and launch a simple store or booking page you can run in fixed time slots.
How to start
- 1
Check your contract
Look for moonlighting, non-compete or conflict-of-interest clauses. When in doubt, ask HR.
- 2
Pick an idea that fits your time
Evening tutoring, weekend dog sitting, photo shoots, furniture assembly or a small online store run well as side businesses.
- 3
Register and plan taxes
Side income is taxable. In the US, you may need quarterly estimated taxes; in the UK, Self Assessment applies above the trading allowance.
- 4
Set your hours
Two evenings and one Saturday, for example. For services, make exactly those slots bookable.
Side business ideas that work
Services with flexible hours: tutoring, language lessons, pet sitting, cleaning, garden help, personal training, social media help for local shops. Products: a small store with trending products, without holding inventory.
FAQ
How much can I earn on the side before paying tax?
It depends on your country. In the UK, the trading allowance covers up to £1,000 of gross trading income per year. In the US, self-employment tax generally applies once net earnings reach $400.
Can my employer stop my side business?
Only in specific cases, for example competition or conflicts with your job. Check your contract.
Do I need a website for a side business?
A simple store or booking page makes you look professional and lets customers buy or book without messaging back and forth.
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More guides for founders
Start an online business
Bookkeeping basics
Business license to sell online
Sole proprietorship vs. LLC
Editorial team 5minstore · Updated: November 1, 2026. General information, not legal or tax advice.