Data Sources

This report from the Georgetown University Center for Children and Families (CCF) uses data from the Centers for Medicare & Medicaid Services (CMS) State Medicaid and CHIP Applications, Eligibility Determinations, and Enrollment Data to analyze total and child enrollment in Medicaid and/or the Children’s Health Insurance Program (CHIP) by state. All states and the District of Columbia are required to report monthly Medicaid and CHIP enrollment data to CMS as part of the Performance Indicator Project. CCF uses updated, rather than preliminary, enrollment data whenever possible.

Where noted, CCF also uses data from CMS’s August 2022 Medicaid and CHIP Enrollment Snapshot, as these snapshots provide additional breakouts not available in the above dataset. CMS, however, uses preliminary data in these snapshots, which may differ from the updated numbers used in CCF’s analyses.

Additionally, because Arizona does not report child enrollment to CMS, CCF substitutes state administrative data for Arizona’s child enrollment numbers in all months. CCF also substitutes state administrative data for Indiana’s total and child enrollment numbers in August 2022 due to recent adjustments to the state’s CMS reporting methodology.

CCF also uses data from the U.S. Census Bureau’s 2021 American Community Survey (ACS) Health Insurance Historical Table HIC-5: Health Insurance Coverage Status and Type of Coverage by State — Children Under 19: 2008 to 2021 for estimates of the total child population in each state for our calculations of the share of children with Medicaid and CHIP coverage by state. Please note that ACS estimates are not adjusted by the Census Bureau (or by CCF) to address the “Medicaid undercount” in survey data when compared to the reported numbers of individuals enrolled in Medicaid and CHIP using federal or state administrative data. Additionally, recent research shows that the undercount in the 2021 ACS was nearly double that in previous years. Young children may be especially likely to be undercounted.

Timing

This paper uses a baseline of February 2020 to measure enrollment growth through August 2022 during the COVID-19 public health emergency and when the related Medicaid continuous coverage requirement was in effect. We use August 2022 enrollment data because at the time of writing, that was the most recent data CMS enrollment data available. On January 31, 2023, however, CMS published updated data for September 2022. Between August and September, an additional 536,034 individuals were enrolled in Medicaid/CHIP, including 217,975 children.