Middle Class Income for a Family. The annual average income for a middle class family of four is approximately $70, 354. This is based on a 2006 report by the U.S. Census for a family of four.This figure is in the middle of the range of incomes for this section of the population. The median income during this time for all households was $48,561.n the 2000s, the middle class took a hit. From 2000 to 2010, income levels for those in the middle class decreased by 7 percent. Conversely, the top tier of Americans, those earning over $186,000, saw their incomes rise.