Regulations governing the Flex Program establish conditions of participation under which rural hospitals are certified as Critical Access Hospitals (CAHs). Among these conditions of participation are standards related to the location of the facility. Specifically, a hospital must be located more than a 35 mile drive (or, in the case of mountainous terrain or in areas with only secondary roads available, a 15 mile drive) from another hospital or CAH to be eligible for certification as a CAH. The regulations also provide an exception to these mileage requirements through the creation of a “Necessary Provider” provision. Under this provision, states may certify hospitals that do not meet the federal mileage requirements, but are important to the delivery of health care services, as Necessary Providers thereby qualifying them for CAH conversion. The Flex Program regulations provide states with the flexibility to define their own criteria by which they will certify Necessary Providers. This provision recognizes that mileage alone is an inadequate measure of access needs. It further recognizes that states are in the best position to develop standards that correspond to their own assessments of the access needs and vulnerability of the health care infrastructure in their states. Each state interested in establishing a Flex Program was required to submit an application to the Regional Administrator of the appropriate Center for Medicare and Medicaid Services (CMS) Regional Office. Each application was to included a description of the criteria used to certify Necessary Providers.This document summarizes the Necessary Provider criteria for each state. This document summarizes the Necessary Provider criteria for each state.