Low grade. The base of 3500 yuan provident fund refers to the base of the monthly contribution of provident fund, which belongs to a low grade, and its proportion ranges from 5% to 12%, depending on the unit. Provident fund refers to housing provident fund. Housing accumulation fund refers to the long-term housing savings paid by state organs and institutions, state-owned enterprises, urban collective enterprises, foreign-invested enterprises, urban private enterprises and other urban enterprises and institutions, private non-enterprise units, social organizations and their employees.