Parents should charge about 10 percent of the child's take-home pay for room and board, according to David Blaylock of Learnvest Planning Services. The amount should be enough that the adult child feels the responsibility of paying for his living expenses.
The amount should be low enough so that staying at home doesn't feel like a burden. Some parents charge their children a fraction of what the adult child would pay to live outside of the home. Since some families encourage their children to move back home after they graduate from college to save money, asking for a reasonable amount of money for household contributions is appropriate without becoming a source of stress for the child.