When I was growing up my parents charged me weekly room and board while still in high school AND had very strict rules along with an early curfew even after I had graduated. For that I got the priveledge of sleeping on the couch and storing my stuff in boxes in their hallway. To this day I have never had a key to their house. (Though I was a really good, responsible kid.)

My daughter is now in college. As long as she remains in school full time and is working hard towards her degree we won't charge her. We do expect certain rules to be followed and to get some help around the house, though that is rarely done. If she were to drop down to part time in school our expectations would change.

My suggestion is that since you see that he does have extra money and are concerned that he isn't saving, charge a modest rent. If you don't need it, save it or even a portion of it, for him. I wouldn't let him know what you are doing because teens have a way of starting to feel ownership then and you could hear about having 'HIS' money. Good Luck!