I definitely think it is a good idea, we always paid my parents something once we were working and still at home. It varied depending on how much we earnt. So my sister who was at uni and just doing part time work may have only paid $50 a fortnight, while I was working fulltime and paying $150 a fortnight. I also think it is important that even if kids pay board, they are still responsible for some of the jobs around the house, otherwise they can see it as a bit of a 'hotel'.