Registered mine once it got serious, here's what I learned. Two separate things people confuse: 1) ACRA business registration, generally required if you're carrying on a business (using a business name, ongoing trade for profit), even small. There's a hobby-vs-business line, occasional selling of personal items isn't a business, but regular selling of handmade goods for profit leans toward 'business'. Registration is cheap and gives you a proper business name + ability to open a business bank account. 2) Income tax, you must declare business/trade income to IRAS regardless of whether you registered, and you can deduct genuine business expenses. GST is a separate threshold thing you only worry about at higher revenue. For a few hundred/month you're small, but declaring income is the safe move. Please verify the current registration criteria and tax rules directly on the ACRA and IRAS sites, don't rely on forum takes for compliance.