Do you need to pay income taxes if you were to daytrade in US market?

There is a pattern day trader rulings for daytrade in US market. To avoid getting flagged, you can either

1) have 25k cash in your trading account

2) join a propieraty trading firm that can margin/leverage your account to bypass the rules (usually more expensive for fees and services)

If trading is your main occupation, yes. I know of people of who trade the US market and hold regular jobs, IRAS has not gone after them for their capital gains and trade gains. So i think the answer is no income tax if not your main job

If day-trading US stocks is your main source or only source of income, then it may be safer for you to declare it under "trade income". Alternatively, you may seek advice from your own tax advisor.​​​

Nope, I think that the 30% withholding tax only applies to dividends if you receive. If I am not wrong, capital gains are not taxable.