How Many Uninsured Are in the Coverage Gap and How Many Could be Eligible if All States Adopted the Medicaid Expansion?
Data and Methods
State Health Access Data Assistance Center. 2013. “State Estimates of the Low-income Uninsured Not Eligible for the ACA Medicaid Expansion.” Issue Brief #35. Minneapolis, MN: University of Minnesota. Available at: http://www.rwjf.org/content/dam/farm/reports/issue_briefs/2013/rwjf404825.
Van Hook, J., Bachmeier, J., Coffman, D., and Harel, O. 2015. “Can We Spin Straw into Gold? An Evaluation of Immigrant Legal Status Imputation Approaches” Demography. 52(1):329-54.
Based on state-reported eligibility levels as of January 2023. Eligibility levels are updated to reflect state implementation of the Medicaid expansion as of March 2023 and 2023 Federal Poverty Levels but may not reflect other eligibility policy changes since January 2023.
Non-MAGI pathways for nonelderly adults include disability-related pathways, such as SSI beneficiary; Qualified Severely Impaired Individuals; Working Disabled; and Medically Needy. We are unable to assess disability status in the ACS sufficiently to model eligibility under these pathways. However, previous research indicates high current participation rates among individuals with disabilities (largely due to the automatic link between SSI and Medicaid in most states, see Kenney GM, V Lynch, J Haley, and M Huntress. “Variation in Medicaid Eligibility and Participation among Adults: Implications for the Affordable Care Act.” Inquiry. 49:231-53 (Fall 2012)), indicating that there may be a small number of eligible uninsured individuals in this group. Further, many of these pathways (with the exception of SSI, which automatically links an individual to Medicaid in most states) are optional for states, and eligibility in states not implementing the ACA expansion is limited.
Technical Appendix A: Household Construction
Steven Ruggles, Sarah Flood, Ronald Goeken, Josiah Grover, Erin Meyer, Jose Pacas, and Matthew Sobek. IPUMS USA: Version 8.0 [dataset]. Minneapolis, MN: IPUMS, 2018. https://doi.org/10.18128/D010.V8.0
For a detailed description of how IPUMS constructs family interrelationships variables, see https://usa.ipums.org/usa/chapter5/chapter5.shtml
According to the Public Use Microdata Sample (PUMS) documentation, "Estimates generated with PUMS microdata will be slightly different from the pretabulated estimates for the same characteristics published on data.census.gov. These differences are due to the fact that the PUMS files include only about two-thirds of the cases that were used to produce estimates on data.census.gov, as well as additional PUMS edits."
Medicaid eligibility in 2021 is based on 2023 poverty guidelines, available at: U.S. Department of Health and Human Services, Office of The Assistant Secretary for Planning and Evaluation, Poverty Guidelines. https://aspe.hhs.gov/topics/poverty-economic-mobility/poverty-guidelines. Tax credit eligibility in 2021 is based on 2020 poverty guidelines, available at: U.S. Department of Health and Human Services, Office of The Assistant Secretary for Planning and Evaluation, 2020 Poverty Guidelines https://aspe.hhs.gov/topics/poverty-economic-mobility/poverty-guidelines/prior-hhs-poverty-guidelines-federal-register-references/2020-poverty-guidelines#guidelines.
See Internal Revenue Service, Publication 501, Table 1.2022: Filing Requirements Chart for Most Taxpayers. Available at: https://www.irs.gov/publications/p501#en_US_2022_publink1000270109.
See Internal Revenue Service, Publication 501, Qualifying Relative. Available at: https://www.irs.gov/publications/p501#en_US_2023_publink1000270109.
A detailed explanation of Medicaid and Marketplace income counting rules can be found in Center on Budget and Policy Priorities webinar available at: http://www.healthreformbeyondthebasics.org/wp-content/uploads/2013/08/Income-Definitions-Webinar-Aug-28.pdf
A detailed explanation of Medicaid and Marketplace HIU size calculations can be found in the Center on Budget and Policy Priorities webinar available at http://www.healthreformbeyondthebasics.org/wp-content/uploads/2013/08/Household-Definitions-Webinar-7Aug13.pdf
This is the same underlying data as the 2023 Health Insurance Marketplace Calculator. Available at: http://kff.org/interactive/subsidy-calculator/ For a more detailed examination of plans available in the Health Insurance Marketplaces in 2023, see Kaiser Family Foundation, How ACA Marketplace Premiums Are Changing by County in 2023. Available at: https://www.kff.org/private-insurance/issue-brief/how-aca-marketplace-premiums-are-changing-by-county-in-2023/.
See Congressional Budget Office, Economic Projections. Available at: https://www.cbo.gov/system/files/2022-05/51135-2022-05-Economic-Projections.xlsx.
See Internal Revenue Service, Publication 501, Table 1.2022: Filing Requirements Chart for Most Taxpayers. Available at: https://www.irs.gov/publications/p501#en_US_2022_publink1000270109.
See Internal Revenue Service, Publication 501, Qualifying Relative. Available at: https://www.irs.gov/publications/p501#en_US_2023_publink1000270109.
Technical Appendix B: Immigration Status Imputation
State Health Access Data Assistance Center. 2013. “State Estimates of the Low-income Uninsured Not Eligible for the ACA Medicaid Expansion.” Issue Brief #35. Minneapolis, MN: University of Minnesota. Available at: http://www.rwjf.org/content/dam/farm/reports/issue_briefs/2013/rwjf404825.
Van Hook, J., Bachmeier, J., Coffman, D., and Harel, O. 2015. “Can We Spin Straw into Gold? An Evaluation of Immigrant Legal Status Imputation Approaches” Demography. 52(1):329-54.
This data source is a change from previous KFF analyses, which used estimates from the Department of Homeland Security.
Pew updates these estimates periodically. We use the most recent estimates available at the time of our analysis, and in some cases incorporate estimates received from correspondence with researchers at Pew prior to their publication - however we do not release these numbers ourselves. We draw on Pew directly for all published data and interpolate years missing from their trend. Our analysis uses the year applicable to the year for the data sets to which we apply the regression model. The most recent estimates as of the time of our analysis were: J Passel, D Cohn. Mexicans decline to less than half the U.S. unauthorized immigrant population for the first time. (Pew Research Center), June 2019. Available at: https://www.pewresearch.org/fact-tank/2019/06/12/us-unauthorized-immigrant-population-2017/.
Indicators that imply legal status include: (i) respondent entered the US prior to 1980, or (ii) respondent is enrolled in any of the following public programs: Medicare, military health insurance, public assistance, Supplemental Security Income, or Social Security Income.
For more information, see SHADAC 2013, footnote 6. The table created for this function contains estimates of the undocumented across 2013-2021.
For more detail, see documentation available at: National Health Interview Survey. 2021 Imputed Income Files. Available at: https://www.cdc.gov/nchs/nhis/2021nhis.htm.
As an example of this calculation, we found that approximately 59% of undocumented uninsured individuals did not have health coverage in 2013. We allow the undocumented rate to drop slightly after 2013. We base the percent drop in the uninsured rate that we see in the KFF's Survey of the Low-Income Population and the ACA (which has a direct measure of citizenship) for 2013 to 2014, which is an 11% decline, to estimate an uninsured rate in 2014 for the undocumented (52%). We use the ratio of that drop relative to the drop for citizens (less than half the scale of the drop for citizens) to estimate a 7% drop from 2014 to 2015, getting us to a 49% uninsured rate in 2015 and repeat this until 2021, resulting in the final undocumented uninsured rate of 46% in calendar year 2021. Prior to implementing this new sampling dimension, we found unrealistic drops in the uninsured rate of the undocumented population that we largely attributed to our prediction model's inability to discern this group from legally-present non-citizens, many of whom are eligible for assistance under the ACA's coverage expansions. Although a few states have implemented programs that allow for coverage of the undocumented population, these programs are state-funded and relatively small in scale compared to the nationwide coverage expansions accompanying the ACA.
Technical Appendix C: Imputation of Offer of Employer-Sponsored Insurance
For example, anyone who did not work during 2021 who then held an offer of ESI in early 2022 would appear incongruous in our CPS-based eligibility model. In the other direction, workers covered by health insurance through their own employer in 2021 who lost their offer of ESI during the early months of 2022 (perhaps due to a job change) would also appear incongruous due to the discrepancy across the two time periods.
Available at: https://www.census.gov/data/datasets/time-series/demo/health-insurance/cps-asec-research-files.html. For more detail about these microdata, see: J. Abramowitz, B. O'Hara. New Estimates of Offer and Take-up of Employer-Sponsored Insurance (US Census Bureau), 2016. Available at: https://www.census.gov/library/working-papers/2016/demo/Abramowitz-2016.html.
For an explanation of affordability, see: KFF. Employer Responsibility Under the Affordable Care Act. July 2019. Available at: https://www.kff.org/infographic/employer-responsibility-under-the-affordable-care-act/.