As soon as you earn a paycheck, I’m not kidding. If you are 15 and you have a job, open a Roth IRA and put some money into it. I have 3 kids and teaching them how to save and invest at an early age is critical, because again, it’s a function of time per above. If they start investing at 15, then their time horizon to retirement is at least 50 years, massive amount of compounding will happen over that period. We are happy to discuss this and other tax and retirement strategies with you.