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MACPAC Releases 2018 Edition of MACStats: Medicaid and CHIP Data Book

New data shows a slight decrease in Medicaid and CHIP enrollment last year


The Medicaid and CHIP Payment and Access Commission (MACPAC) today released the December 2018 edition of the MACStats: Medicaid and CHIP Data Book, with updated data on national and state Medicaid and CHIP enrollment, spending, benefits, and beneficiaries’ health, service use, and access to care. Included in this year’s data book is an updated Exhibit 11, showing that total enrollment growth in Medicaid and the State Children’s Health Insurance Program (CHIP) decreased 2.2 percent nationally from July 2017 to July 2018.

Last year’s dip in enrollment comes after two years of modest growth following the initial surge in enrollment due to expansion of Medicaid to the new adult group under the Patient Protection and Affordable Care Act (ACA, P.L. 111-148, as amended)—about 1.3 percent from 2015 to 2016 and about 1.6 percent from 2016 to 2017. Although Medicaid enrollment growth varied by state, 37 states and the District of Columbia saw a decrease in enrollment in 2018. These included states that did not expand Medicaid such as Kansas (where enrollment decreased by 4.1 percent), and those that did expand, such as Colorado (which experienced a 4.4 percent decrease in enrollment).

The updated data book brings together Medicaid and CHIP statistics that are often difficult to find from multiple sources. “A single source for data on Medicaid and CHIP makes MACStats indispensable for federal and state policymakers, reporters, researchers, health care stakeholders, and anyone who seeks to understand Medicaid and CHIP’s impact across the country and in each individual state,” said MACPAC Chair Penny Thompson.

MACStats is published annually in December as well as updated regularly on The data book provides a comprehensive, detailed look at Medicaid and CHIP. More highlights from this year’s edition of MACStats include:

  • In 2017, more than one-quarter of the U.S. population was enrolled in Medicaid or CHIP at some point during the year: 85.3 million in Medicaid and 9.5 million in CHIP (Exhibit 1).
  • Over 40 percent of all individuals enrolled in Medicaid or CHIP in 2017 had family incomes below 100 percent of the federal poverty level (FPL). About 59 percent of all individuals enrolled in Medicaid or CHIP had incomes of less than 138 percent FPL, the threshold used to determine eligibility for Medicaid in states that have expanded Medicaid to low-income adults (Exhibit 2).
  • In fiscal year (FY) 2017, Medicaid accounted for 9.4 percent of the federal budget, a smaller share than Medicare (14.9 percent) (Exhibit 4).
  • Medicaid’s share of state-funded budgets (excluding federal funds) and total state budgets (including federal funds) has varied over time. In state fiscal year 2015, Medicaid’s share of total state budgets increased, but its share of state-funded budgets decreased slightly—the decrease can be attributed to 100 percent federal funding made available in that year for low-income adults not otherwise eligible on the basis of disability, who became newly eligible for Medicaid under the ACA (Exhibit 13). Federal funds for this group of low-income adults gradually decline until FY 2020 and thereafter, when the matching rate reaches 90 percent.
  • Drug rebates reduced gross Medicaid drug spending by more than half (54.5 percent) in FY 2017 (Exhibit 28). Gross drug spending increased 5.2 percent from FY 2016, but net drug spending (i.e., after rebates) decreased by 1.7 percent. Over half (62.4 percent) of Medicaid gross spending for drugs occurred under managed care in FY 2017 (Exhibit 26).
  • Both children and adults whose primary coverage source was Medicaid or CHIP reported seeing the doctor slightly less than those with private coverage, but more than those who are uninsured. (Exhibits 40 and 46).

Visit this link for the PDF and spreadsheet versions of the December 2018 MACStats: Medicaid and CHIP Data Book. Visit for MACPAC’s newest issue briefs on Access in Brief: Pregnant Women and Medicaid and findings from case studies on Medicaid eligibility, enrollment, and renewal. Follow us on Twitter @macpacgov.



The Medicaid and CHIP Payment and Access Commission is a non-partisan legislative branch agency that provides policy and data analysis and makes recommendations to Congress, the Secretary of the U.S. Department of Health and Human Services, and the states on a wide array of issues affecting Medicaid and CHIP. For more information, please visit