The Patient Protection and Affordable Care Act (ACA; P.L. 111-148 , as amended) created a permanent risk adjustment program that aims to reduce some of the incentives insurers may have to avoid enrolling individuals who are at risk of high health care costs in the private health insurance market—specifically in the individual (nongroup) and small-group markets. Section 1343 of the ACA established the risk adjustment program, which is designed to assess charges to health plans that have relatively healthier enrollees compared with other health plans in a given state. The program uses collected charges from plans with comparatively healthy enrollees to make payments to plans in the same state that have relatively sicker enrollees. The Centers for Medicare & Medicaid Services (CMS) administers the risk adjustment program as a budget-neutral program, so that payments made are equal to the charges collected in each state. Risk adjustment transfers are intended to account for differences in health risk among plans in each state while allowing for premium differences based on allowable rating factors. CMS assesses payments and charges on an annual basis, beginning in the 2014 benefit year. All nongrandfathered, individual market and small-group market health plans, both inside and outside of the exchanges, participate in this program. Prior to the ACA, most state laws (and federal law under limited circumstances) allowed insurers to minimize their exposure to high-risk individuals by charging higher or lower premiums to potential enrollees based on factors such as age, gender, and health status. However, under current federal law, insurers in the individual and small-group markets are unable to set premiums based on gender or health status and are limited in how much they may vary premiums by age. Without being permitted to account for the risk from individuals who expect or plan for high use of health services on the basis of the aforementioned criteria, insurers still may attempt to avoid such individuals by using benefit designs, networks, formularies, and/or marketing techniques that are not likely to appeal to them (though insurers are limited by other ACA requirements, such as being required to offer coverage for the Essential Health Benefits). Under the ACA's permanent risk adjustment program, the Secretary of the Department of Health and Human Services (HHS) established criteria and methods to determine the actuarial risk of plans within a given state in order to make payments and assess charges. Enrollees in health plans differ in their degree of risk based on such factors as their health status, with sicker individuals considered high risk and expected to have greater health costs than healthier, or low-risk , individuals. Individuals who perceive themselves as high risk, as opposed to those who perceive themselves as low risk, are likely to have different behaviors related to health insurance. High-risk individuals, who perceive that they will need more health services, may be more motivated to seek out and enroll in plans with more comprehensive coverage and benefits than might low-risk individuals. Since individuals have more information about their own health status than does an insurer, they are able to consider this information when choosing a health plan; by contrast, an insurer is not able to take this information into account when establishing coverage, benefits, and premiums for the plan. The risk adjustment program is intended to reduce the likelihood that an insurer will aim to enroll only low-risk individuals and help ensure that price differences of plans reflect the plan design and benefits available rather than risk. Risk adjustment is a risk mitigation strategy that has been incorporated into other insurance programs. It is a component of the Medicare program, as well as some state Medicaid programs. Other countries with regulated, private health insurance markets, such as the Netherlands, Switzerland, Germany, Australia, and South Africa, also have risk adjustment mechanisms. In addition, risk adjustment was part of the Commonwealth Care program in Massachusetts from 2009 through 2016. Although risk adjustment programs may have similar aims, program designs may vary. HHS used the Medicare risk adjustment program as the basis for the ACA risk adjustment program, although HHS made modifications especially to account for the different populations in the programs. The risk adjustment program is the only permanent program that was part of the three ACA risk mitigation programs, including the transitional reinsurance program and the temporary risk corridors program. This report provides responses to frequently asked questions related to the risk adjustment program. The first several questions pertain to background on insurance markets, why risk mitigation matters, and the role of risk adjustment in risk mitigation. The following questions relate to the mechanics of the risk program, including how enrollee risk scores are calculated and how risk adjustment payments and charges are determined. Responses to the concluding questions provide information on the experience of the risk adjustment program thus far and future changes to the program. Understanding the sources of private health insurance coverage and how such coverage is regulated at the federal level may be useful in providing context around the current federal law and the permanent risk adjustment program (see text box "Sources and Regulation of Private Health Insurance Coverage"). The concept underlying insurance is risk (i.e., the likelihood and magnitude of experiencing a financial loss). In any type of insurance arrangement, all parties seek to manage their risk, subject to certain objectives (e.g., coverage and/or profit goals). In health insurance, consumers (or patients, as insurance enrollees) and insurers (as sellers of insurance) approach the management of health insurance risk differently. From the consumer's point of view, a person (or family) buys health insurance to protect against financial losses resulting from the unpredictable use of potentially high-cost medical care. The insurer employs a variety of methods to manage the risk it takes on when providing health coverage to consumers to assure that the insurer operates a viable business (e.g., balancing premiums against the collective risk of the covered population). The insurer uses these methods when pooling risk so that premiums collected from all enrollees generally are sufficient to fund claims (plus administrative expenses and profit). Where insurers have discretion, they are likely to act in their own financial self-interest to limit their exposure to risk. Prior to the ACA, insurers in the individual and small-group markets could assess the risk of an individual or group applying for insurance coverage using characteristics such as health status, gender, and age with certain exceptions. Using such characteristics, insurers could charge higher premiums for higher-risk individuals, or they could deny coverage if an individual represented too much risk, so long as the denial of coverage was permitted under state law. Similarly, before the ACA, an individual with a preexisting condition may have had that condition excluded from coverage or coverage for a preexisting condition may have been delayed for a period of time (e.g., 6 to 36 months, or indefinitely) depending on state laws and other federal requirements. The converse was also true—insurers had been able to charge lower premiums to lower-risk individuals based on health status, gender and age, with some exceptions. The ACA includes provisions that aim to restructure the private health insurance market by implementing several market reforms targeting the individual and small-group markets, including some that impose requirements on health insurance plans. As part of a larger set of private health insurance market reforms, the ACA requires private health insurers to provide coverage to individuals regardless of health status, medical history, and preexisting conditions. Prior to the ACA, insurers in the small-group market already were prohibited from denying coverage based on these factors. Under current federal law, insurers can adjust premiums based solely on certain factors (i.e., individual or family enrollment, geographic rating area, tobacco use, and age). Additional market reforms aim to expand the pool of individuals seeking to purchase health insurance coverage. Under the ACA reforms, some individuals may be eligible for financial assistance (i.e., premium tax credits and cost-sharing subsidies) through the health insurance exchanges (also known as the marketplaces ), which may make these individuals more likely to purchase health insurance. In addition, the ACA, as originally enacted, had required that most individuals maintain health insurance coverage or pay a penalty for noncompliance (i.e., the individual mandate ), but the penalty associated with the individual mandate will be effectively eliminated beginning in 2019. The expanded pool created by the ACA reforms contributes to the uncertainty that insurers face. (Uncertainty was particularly high in the early years of ACA implementation.) Much of the uncertainty centers on the types of individuals who may or may not seek coverage in the expanded pool. For example, to what extent will healthy individuals decide to seek coverage in addition to unhealthy individuals? Also, will the expanded pool extend to individuals who previously were uninsured and/or may have delayed receiving health care services? Furthermore, what will be the demand for health care services for this expanded pool of individuals? In addition to the risks and uncertainty described above, one phenomenon that exists in health insurance markets is that individuals who expect or plan for high use of health services are more likely to seek out coverage and enroll in plans with more benefits than individuals who do not expect to use many or any of the health services. Prior to the ACA, state law (and federal law, under limited circumstances) determined whether insurers could minimize their exposure to this risk by charging higher or lower premiums to potential enrollees based on factors such as gender, age and health status. However, under current federal law, insurers in the individual and small-group markets are unable to set premiums based on gender or health status, and insurers are limited in how much they can vary premiums by age. Notwithstanding this change, and although insurers are limited by other ACA requirements, insurers still could attempt to gain a competitive advantage by avoiding individuals who expect or plan for high use of health services (e.g., sicker, older individuals) by using benefit designs, networks, formularies, and/or marketing techniques that are not likely to appeal to these individuals.