We're starting early. My 14 year old has two jobs (mowing lawns/ shoveling snow & a paper route) and he already has $320 in his roth IRA account. He invests 10% of all the money he makes.
He *loves* earning and spending money - and he makes careful choices that I'm really proud of. Just this week he paid to go to 6 Flags with the park district and last month both he and his brother paid their own tickets to see Weird Al in concert!
