What estimates exist (Census, KFF, Urban Institute) for health coverage among noncitizens and undocumented populations in 2022–2023?

1. Why the headline numbers differ — big-picture contrasts that matter

Different methods and definitions yield materially different headline figures: the Urban Institute’s modeling projects about 8.7 million uninsured noncitizens and that noncitizens account for roughly 31–32% of the uninsured ^[1]. KFF’s 2023 KFF/LA Times survey reports that about half of likely undocumented adults are uninsured, with nearly one in five lawfully present immigrants uninsured—contrasting with 6% for naturalized citizens—highlighting a gradient by immigration status rather than a single aggregate number ^{[2] [4]}. The Census Bureau’s 2023 report does not release a direct undocumented-specific tally but shows noncitizens represent about a quarter of the uninsured in its broad aggregates and that nearly one-third of noncitizens lacked insurance in 2023, which aligns conceptually with the high uninsured rates reported by the other analyses even if precise counts differ ^{[3] [5]}. Differences stem from survey sampling, definitions of “noncitizen” and “likely undocumented,” and modeled assumptions about eligibility and take-up.

2. Magnitude and composition — how many, who they are, and where they live

Across sources, millions of noncitizen adults are uninsured, concentrated in the South and West and among lower-income and working-age populations. Urban Institute’s projections show noncitizens under 65 representing about 8% of the population but nearly a third of the uninsured—about 8.7 million uninsured noncitizens—and estimate that lifting immigration-specific restrictions would make roughly 5.7 million of those uninsured eligible for public or subsidized coverage ^[1]. KFF’s survey finds large disparities by legal status and state policy, with uninsured rates much higher among likely undocumented immigrants and among those in states without Medicaid expansion or state-funded immigrant programs ^{[2] [4]}. Census aggregates underscore regional concentrations and the persistence of long-term uninsurance for many noncitizens ^{[3] [5]}.

3. Policy eligibility is the proximate cause — what the analyses identify as levers

All sources identify immigration-related eligibility restrictions as the primary proximate driver: federal law bars many noncitizens from Medicaid/CHIP and certain Marketplace subsidies, and lawfully present immigrants face a five-year waiting period in many cases; states that provide expanded, state-funded coverage to immigrants show much lower uninsured rates among immigrant adults ^{[5] [2]}. Urban Institute quantifies the impact: 2.2 million uninsured noncitizens could become Medicaid/CHIP-eligible and 3.5 million could gain Marketplace premium tax credit eligibility if immigration-specific limits were lifted ^[1]. KFF’s survey corroborates the policy linkage and highlights that employer coverage gaps—due to employment in jobs less likely to offer insurance—compound eligibility barriers ^[2].

4. State policy differences — patchwork solutions with measurable effects

State-level policy choices materially change coverage outcomes. KFF’s analysis shows immigrants in states that adopted ACA Medicaid expansion and immigrant coverage expansions are roughly half as likely to be uninsured as those in states without such policies ^{[2] [4]}. The Census report documents regional concentration of the uninsured in the South and West and notes that state-funded programs for children, pregnant people, or select groups mitigate federal ineligibility in some places ^{[3] [5]}. Urban Institute’s modeling indicates that state action could reduce the number of uninsured among noncitizens substantially, reinforcing that state policy is the clearest lever to reduce uninsurance short of federal immigration eligibility reform ^[1].

5. Economic context and fiscal framing — taxes paid versus emergency spending

The sources underscore a recurring fiscal tension: undocumented immigrants contribute sizeable tax revenues while being largely ineligible for most federal benefits. One synthesis notes undocumented immigrants paid an estimated $20.1 billion in federal taxes and $11.8 billion in state/local taxes in 2018 and that emergency Medicaid spending for undocumented immigrants was about $974 million in 2016, a tiny share of total Medicaid outlays ^[6]. This framing is used by proponents of expanded access to argue cost-sharing benefits and by opponents to emphasize legal constraints; the data show the fiscal impact is real but not on a scale that explains the high uninsured rates, which are driven mainly by legal eligibility and employer coverage gaps ^{[6] [1]}.

6. What’s missing and why uncertainty continues — data gaps and methodological caveats

Precise, contemporaneous counts of undocumented coverage are inherently uncertain because major federal surveys avoid direct documentation questions or undercount hard-to-reach populations. Census CPS/ACS-based tables provide robust coverage trends but do not enumerate undocumented residents directly; KFF survey work uses "likely undocumented" proxies and Urban Institute relies on modeling to translate survey and administrative inputs into estimates and eligibility scenarios ^{[1] [4]}. These methodological limits mean statements about exact counts should be read as best estimates with clear sensitivity to definitions and state policy assumptions, but the consistent direction across diverse methods—very high uninsured rates among noncitizens and large potential gains from removing eligibility restrictions—is firm ^{[6] [1] [5]}.