Established as part of the Patient Protection and Affordable Care Act (ACA; P.L. 111-148 , as amended), the Independent Payment Advisory Board (IPAB) is charged with developing proposals to "reduce the per capita rate of growth in Medicare spending." The board's proposals are to be implemented by the Secretary of Health and Human Services (the Secretary) unless Congress acts either by formulating its own proposal to achieve the same savings or by discontinuing the automatic implementation process defined in the statute. Historic patterns of growth in overall health care spending, and in the Medicare program in particular, are viewed as not being sustainable. As the 2017 Medicare Trustees report recently noted, Medicare faces "a substantial financial shortfall that will need to be addressed with further legislation. Such legislation should be enacted sooner rather than later to minimize the impact on beneficiaries, providers, and taxpayers." Several proposals have been advanced over the years to create an independent policymaking entity that would (1) be charged with limiting the future growth in Medicare expenditures; (2) be insulated from special interests and lobbyists because its members would be appointed, rather than elected; and (3) be comprised of officials who would serve for extended terms. Such officials were envisioned to be able to make "hard decisions" to control rising costs. Moreover, it has been assumed that these officials would possess the specialized expertise needed to make operational decisions regarding payments and focus initiatives on beneficiary interests and the longer-term financial viability of the program. Prior proposals for similar entities include the following: In 2000 and 2001, Senators Breaux and Frist introduced reform proposals to increase the budget of the Centers for Medicare and Medicaid Services (CMS), create separate agencies to administer parts of the Medicare program, and establish a Medicare board to manage competition among private plans and traditional Medicare (referred to as "Breaux-Frist I," S. 1895 , and "Breaux-Frist II," S. 358 ). In 2008, Senator Daschle proposed the Federal Health Board, modeled after the Federal Reserve Board, with broad authority over both private and public health care programs, including benefit and coverage recommendations, regulation of private insurance markets, and improvements in quality of care. In July 2009, then-President Obama submitted a draft proposal to Congress titled the Independent Medicare Advisory Council Act of 2009 (referred to as the IMAC proposal), that would have established a five-member council to advise the President on Medicare payment rates for certain providers. While the council would have had authority to recommend broader policy reforms, its authority outside of Medicare payment policy would have been limited. The stated goal of the IPAB, as specified in the enabling statute, is to reduce the per capita growth in Medicare expenditures. The IPAB would achieve this goal by developing proposals for the Secretary to implement that reduce the growth in Medicare expenditures. By statute, the IPAB's proposals must (1) relate only to the Medicare program; (2) result in a net reduction in total Medicare program expenditures at least equal to the savings target established by the Chief Actuary of CMS [to reduce the expenditure per capita growth rate]; (3) not include any recommendation to ration care, raise revenues or Medicare beneficiary premiums, increase cost sharing, restrict benefits, or alter eligibility; (4) not reduce payments to providers or suppliers scheduled to receive a reduction in payment as the result of certain productivity adjustments under ACA Section 3401; (5) include recommendations to reduce Medicare payments under Parts C and/or D; and (6) include recommendations with respect to administrative funding for the Secretary to carry out the board's recommendations. The IPAB's proposals would receive special status, as described below, including "fast-track" procedures for congressional consideration. The Congressional Budget Office (CBO), in its cost estimate of the ACA prior to passage, projected that the cumulative impact of the board's recommendations from 2015 through 2019 would reduce total spending by $15.5 billion; during the same period, total Medicare expenditures were projected to be $3.9 trillion with average spending per beneficiary increasing from $13,374 in 2015 to $15,749 in 2019. These savings represent a reduction of about $60.00 per year per Medicare beneficiary over the 2015 through 2019 period. Since the ACA was enacted (and the IPAB authorized), there have been several challenges to the mission, authority, and constitutionality of the IPAB. In particular, critics have noted the special procedures that IPAB bills would receive and the board's ability and powers to affect federal health care programs specifically and the health care sector more broadly. Each of these concerns is addressed in the questions below. Section 1899A of the Social Security Act (SSA) requires the Chief Actuary of CMS to determine by April 30, 2013, and annually thereafter, whether the projected five-year average growth in per capita Medicare program spending exceeds a specified target. Such a determination would trigger a series of actions. For determination years through 2017, the target is equal to the average of the projected five-year average growth in the Consumer Price Index for All Urban Consumers (all categories; United States city average, or CPI-U) and the medical care expenditure category of the CPI-U. Beginning in 2018 and in subsequent years, the target growth rate will be the projected five-year average percentage increase in the nominal gross domestic product per capita plus one percentage point (GDP+1%). The five years to be used for a given determination year consist of the two prior years, the current year, and the two following years; thus, the growth rates used in the determination will include both actual and projected rates. If the Chief Actuary finds that the growth rate does not exceed the targeted growth rate, the process for the year ends. If the Chief Actuary determines that the growth rate exceeds the target growth rate for any determination year, the Chief Actuary is required to establish an applicable savings target for the implementation year, two years following the determination year. The board is to be composed of 15 members appointed by the President with the advice and consent of the Senate for up to two consecutive six-year terms. As such, the members would be officers of the United States under the appointments clause of the U.S. Constitution. The Secretary, the Administrator of CMS, and the Administrator of the Health Resources and Services Administration (HRSA) would be ex-officio nonvoting members. In selecting individuals for nomination, the President is to consult with the majority and minority leadership of the Senate and House of Representatives—each respectively, regarding the appointment of three members. The chairperson is to be appointed by the President, with the advice and consent of the Senate, from among the members of the board. The appointed members of the board are to represent varied professional and geographic backgrounds and possess recognized expertise in health finance and economics, actuarial science, health facility management, health plans and integrated delivery systems, and reimbursement of health facilities. The members are to be drawn from a wide range of backgrounds, including but not limited to physicians (allopathic and osteopathic) and other health professionals, providers of health services, and related fields; experts in the area of pharmaco-economics or prescription drug benefit programs; employers; third-party payers; and individuals skilled in the conduct and interpretation of biomedical health services and health economics research who have expertise in outcomes and effectiveness research and technology assessment. Board members are to include representatives of consumers and the elderly. A majority of the appointed members cannot be individuals directly involved in the provision or management of the delivery of Medicare items and services. The appointments would be for full-time service and members would be compensated at Executive Schedule rates. In brief, the IPAB has yet to be constituted and no members have been nominated (let alone confirmed) because the conditions that would trigger IPAB activity have yet to be met. The CMS Chief Actuary's IPAB determination website details the calculations that compare the projected five-year average growth in per capita Medicare program spending to the IPAB target. The CMS Chief Actuary's 2017 IPAB determination states that "[b]ecause the projected 5-year Medicare per capita growth rate does not exceed the Medicare per capita target growth rate, there is no applicable savings target for implementation year 2019 (determination year 2017)." This result is a change from the 2016 and 2015 Medicare Trustees reports, which each projected that the Medicare spending per capita growth rate would exceed the per capita target growth rate in 2017. The underlying data used in the 2017 IPAB determination show that the five-year average growth rate in Medicare per capita expenditures was lower than in the 2016 IPAB determination, whereas the target growth rate (based on the CPI-U) was higher than in the 2016 determination. This caused a divergence of the two trends (see Figure 1 ). The first year of the IPAB activation is no longer 2017 but is now 2021, according to the latest IPAB determination. As seen in Table 1 , the actual 2016 Medicare per capita growth rate (1.11%) was less than two-thirds the value of the 2016 determination projected rate (1.79%), whereas the 2017 determination projections for the 2017 (0.44%) and 2018 (1.51%) values are each lower than the 2016 determination projections (1.10% for 2017 and 4.32% for 2018). For the CPI-U and medical CPI-U growth figures, three out of the four overlapping years (out of the five-year moving averages) show higher values in the 2017 determination compared with the 2016 determination. These differences combined to lower the five-year average Medicare per capita growth rate while raising the CPI-U-based IPAB target growth rate, switching the comparison for 2017 from positive in the 2016 determination (Medicare per capita growth rate greater than IPAB target growth rate) to negative in the 2017 determination. The projected future IPAB determinations can be seen in Figure 1 .