low-income families
(10) The term “low-income families” means families whose incomes do not exceed 80 percent of the median income for the area, as determined by the Secretary with adjustments for smaller and larger families, except that the Secretary may establish income ceilings higher or lower than 80 percent of the median for the area on the basis of the Secretary’s findings that such variations are necessary because of prevailing levels of construction costs or fair market rents, or unusually high or low family incomes.