The federal Health Center Program awards grants to support health centers: outpatient primary care facilities that provide care to primarily low-income individuals. The program is administered by the Health Resources and Services Administration (HRSA)—specifically by its Bureau of Primary Health Care—within the Department of Health and Human Services (HHS). The federal Health Center Program is authorized in Section 330 of the Public Health Service Act (PHSA) and supports four types of health centers: (1) community health centers, (2) health centers for the homeless, (3) health centers for residents of public housing, and (4) migrant health centers. According to HRSA data, over 10,000 unique health center sites (i.e., individual health center facility locations) exist. These sites provided care to 24.3 million people in 2015. The majority of health center sites are community health centers (CHCs). CHCs serve the general low-income or otherwise disadvantaged population, whereas the remaining three types of health centers provide care to more targeted low-income or otherwise disadvantaged populations (e.g., migrant farmworkers). Regardless of type, health centers are required by statute to provide health care to all individuals located in the health center's service area or individuals who are members of the health center's target population, regardless of their ability to pay. Health centers are also required to be located in geographic areas that have few health care providers or to provide care to populations that are medically underserved. These requirements make health centers part of the health safety net—providers that serve the uninsured, the underserved, or those enrolled in Medicaid. Data compiled by HRSA demonstrate that health centers primarily serve the intended safety net population, as the majority of patients are uninsured or enrolled in Medicaid. This report provides an overview of the federal Health Center Program, including its statutory authority, program requirements, and appropriation levels. The report then describes health centers in general, where they are located, their patient population, and outcomes associated with health center use. It also describes the federal programs available to assist health center operations, including the federally qualified health center (FQHC) designation for Medicare and Medicaid payments. Finally, the report has two appendixes that describe (1) FQHC payments for Medicare and Medicaid beneficiaries served at health centers and (2) programs that are similar to health centers but not authorized in Section 330 of the PHSA. Two companion reports also provide additional information about health center supplemental funding (CRS Report R43911, The Community Health Center Fund: In Brief ) and about family planning services provided at health centers (CRS Report R44295, Factors Related to the Use of Planned Parenthood Affiliated Health Centers (PPAHCs) and Federally Qualified Health Centers (FQHCs) ). The federal Health Center Program awards grants to support outpatient primary care facilities that provide care to primarily low-income individuals. This section of the report describes the statutory authority for the federal Health Center Program, program requirements, types of grants awarded in support of the Health Center Program, the Health Center Program's appropriation, and other funding/revenue that health centers receive. Section 330 of the PHSA authorizes grants for health centers and includes the requirements that entities must meet to receive a health center grant. Section 330 requires health centers to provide services to the entire population located in the health center's service area or individuals who are members of the health center's target population, regardless of individuals' ability to pay. Health centers are also required to document the health needs of the residents in their service area and to update their service area if upon evaluation they determine that changes are needed. Among other program requirements, health center grantees must (1) be located in specific geographic areas, (2) have an established fee schedule that meets certain requirements, (3) collect reimbursements for individuals enrolled in public or private insurance programs, (4) have appropriate governance, (5) offer specific health services, (6) meet certain reporting and quality assurance requirements, and (7) license providers and seek accreditation. These requirements apply to activities that are within the scope of PHSA Section 330 grant, but do not apply to other activities. HRSA is required to determine whether health center grantees meet these requirements. In 2012, the Government Accountability Office (GAO) raised concerns that the agency may not be providing sufficient oversight of the program and that some health centers may not be meeting these requirements. In response to this GAO report, HRSA implemented new procedures to increase the agency's oversight of the program and to provide training to health centers to better comply with the program's requirements. This CRS report does not evaluate whether health centers meet program requirements; rather, it describes the program's requirements. PHSA Section 330 requires that a health center be located in an area designated as medically underserved or as serving a population designated as "Medically Underserved" (see text box ). Health centers must establish their own fee schedules that are consistent with prevailing local rates for health services and are designed to cover the reasonable costs that the health center incurs in providing services. This fee schedule is used by all payers. As part of the requirement to provide services to all individuals regardless of their ability to pay, the health center is required to discount the fee schedule to reduce or waive the amount that the patient pays based on the patient's ability to pay as determined by a patient's income relative to the federal poverty level and the patient's family size—no other criteria may be considered. This is referred to as sliding-scale fees. The statute requires that individuals whose income is above 200% of the federal poverty level pay full charges, while individuals whose incomes are at, or below, 100% of the federal poverty level pay only nominal fees. Individuals with insurance coverage may also be eligible for discounted services if the copayment charged by the individual's health insurance plan would be greater than the amount that the individual would pay for the service under the discounted fee schedule. In this case, the individual would pay only the discounted fee schedule amount and not the full copayment amount as long as this is not precluded by the insurance plan's contract terms. The fee schedule is intended to have patients be monetarily invested in their care but is also supposed to minimize cost-related barriers to care. Health centers are required to enroll as providers in state Medicaid and State Children's Health Insurance Program (CHIP) plans to provide services to beneficiaries enrolled in these programs. They are also required to seek appropriate reimbursement for their costs from third-party payers such as private insurance plans, Medicare, Medicaid, and CHIP. Health centers are further required to have systems to obtain reimbursements, including those used for billing, credit, and collections. These collections provide nearly two-thirds (62.5%) of the Health Center Program's revenue in FY2015 (see Table 4 ). Although health centers collect reimbursements, some data suggest that these reimbursements may not be sufficient to cover the costs that health centers accrue when providing care. For example, the National Association of Community Health Centers (NACHC)—the main advocacy group for health centers at the national level—reported in 2016 that the amount collected from Medicaid covered 82% of the costs incurred when providing care to a Medicaid beneficiary. In a 2010, GAO reported that Medicare reimbursements were also below the amount incurred per patient. In nearly 70% of visits that GAO examined in 2007, the health center's costs exceeded Medicare's upper payment limit (i.e., the maximum amount that Medicare would pay). Since GAO's report, the Medicare payment methodology used for health centers has changed, resulting in increased payments. It is not clear whether the new payment rate fully pays the costs incurred. Health centers are required to have governing boards in which their patients form majorities. For each health center's board, such members are selected to reflect the demographic characteristics of the population served by the health center. Board members are not permitted to be health center employees or their relatives. In addition, nonpatient board members must be representative of the community that is served by the health center, have expertise in fields relevant to health center operations, and no more than half of the nonpatient representatives may derive more than 10% of their income from the health care industry. The governing board must approve general health center policies, including the center's budget, operating hours, management, and fee schedule. The governing board is required to meet monthly, and it must approve the center's director and must approve grant applications submitted by the center. Health centers are required to provide primary health services and preventive and emergency health services. Primary health services are those provided by physicians or physician extenders (physicians' assistants, nurse clinicians, and nurse practitioners) to diagnose, treat, or refer patients. Primary health services include relevant diagnostic laboratory and radiology services. Preventive health services include well-child care, prenatal and postpartum care, immunization, family planning, health education, and preventive dental care. Emergency health services refer to the requirement that health centers have defined arrangements with outside providers for emergent cases that the center is not equipped to treat and for after-hours care. Health centers are also required to provide additional health services that are not primary health services but that are necessary to meet the health needs of the service population. This includes, but is not limited to, behavioral health services and environmental health services. Health center physicians must also have admitting privileges at one or more hospitals located near the health center. This requirement is intended to ensure care continuity for hospitalized health center patients. In instances where a health center physician does not have admitting privileges at a nearby hospital, the health center is required to establish other arrangements to ensure care continuity. Health centers are also required to provide enabling services such as translation services, health education, and transportation for individuals residing in a center's service area who have difficulty accessing the center.