I have a personal finance management question. I want to help my 20-year old nephew establish a budget. He will be starting his first full time job next month. His take home pay will be about $2000 per month. He lives with his mother and I suggested that he start paying her rent, as the rental housing market has skyrocketed in this area and she's paying close to $1800/month on a $55K income. He also wants (and needs) to purchase a car to commute to work. What percentage of his income should be set aside for rent, transportation, car payment, entertainment, incidentals and savings? Seems like the old formula doesn't apply anymore, like the 30% (max) for rent/mortgage, especially in this area.