How much amount of money do you need to accumulate in order to invest it for passive income?

just enough to feed yourself so that you can have free time to do whatever you want? How much would a rental apartment cost? How much would a house cost?

What is the maximum amount of passive income a child can have before they are taxed at their parent’s rate?

I live in Texas and would like to know how much I can pay my child passive income before she is taxed at my tax rate. thanks