The assessment may be paid monthly, quarterly, or annually; generally the more amenities provided the more frequent the assessment must be paid. Some associations operate little or no common property, and the expenses relate solely to enforcement of use restrictions or assumed services. Others are effectively private towns, with elaborate amenities including private roads, street lights, services, utilities, commonly owned buildings, pools, and even schools. Assessments paid to homeowner associations in the United States amount to billions of dollars a year, but are not classed as property taxes.