Nearly 3 Million Uninsured Adults Would Gain a Path to Medicaid Coverage if Their States Adopted ACA Medicaid Expansion

As part of the Affordable Care Act’s (ACA’s) Medicaid expansion, 40 states and Washington, D.C. have extended Medicaid eligibility to adults with incomes up to 138 percent of the federal poverty level (FPL), or about $22,000 for an individual. In these states, Medicaid expansion has substantially expanded access to affordable health coverage for millions of people, helping to drive the uninsured rate to record lows. Nevertheless, congressional Republicans and President Trump enacted unprecedented and harmful changes to the Medicaid expansion in last year’s reconciliation law, including a work requirement and more frequent eligibility redeterminations.^[1]

Despite the changes in the Republican reconciliation law, Medicaid expansion remains a critical source of coverage for people with low incomes, many of whom lack access to affordable health coverage through other sources. In the ten remaining non-expansion states, an estimated 2.7 million uninsured adults could become eligible for Medicaid under the expansion, according to CBPP analysis of 2024 data.^[2] Non-expansion states should provide these adults with a path to low-cost comprehensive health coverage by adopting Medicaid expansion.

Adopting Medicaid Expansion Would Help Diverse Group of People in Non-Expansion States

Uninsured adults who could become newly eligible for Medicaid if their states adopted expansion are racially and ethnically diverse: 66 percent are people of color, compared to 45 percent of the total U.S. population. (See Figure 1.) About 3 in 4 uninsured adults in the expansion-eligible population live in working families, and 1 in 3 are parents caring for children. They are disproportionately likely to be self-employed and to have a disability. About 16 percent of uninsured adults who could become eligible under Medicaid expansion are employed in their own business, professional practice, or farm, compared to 9 percent of other working adults. Some 15 percent have a disability, compared to 11 percent of other adults. And 15 percent of expansion-eligible uninsured adults live in rural areas. (See Figure 2.)

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Adopting Medicaid expansion would:

• improve people’s health and save lives;
• reduce medical debt and increase people’s financial security;
• reduce racial and ethnic disparities in health coverage;
• provide a source of coverage to workers in low paying jobs who lack access to coverage through an employer and their families;
• improve coverage and access to care for children whose parents newly gain coverage; and
• allow people with disabilities to obtain Medicaid coverage based on their income without having to meet strict Supplemental Security Income eligibility criteria.^[3]

While the Republican reconciliation law adds limitations on Medicaid financing and provider payment options for expansion states, adopting Medicaid expansion will still provide benefits to state budgets and providers.^[4]The federal government pays 90 percent of the costs of coverage through expansion. And studies show that Medicaid expansion has produced savings in other areas of state budgets that have largely offset the remaining 10 percent of the costs that states have to cover.^[5] This includes savings in other parts of Medicaid, savings in other state programs serving uninsured populations, increased state revenues, and reductions in uncompensated care. Medicaid expansion has also reduced the cost of providing uncompensated care for providers.^[6] Rural hospitals have been especially likely to benefit from expansion, as they tend to have thin operating margins and higher uncompensated care costs.^[7]

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Those Who Could Become Eligible for Medicaid Expansion Include Adults in the Coverage Gap and Adults Currently Eligible for Premium Tax Credits

Of the 2.7 million uninsured adults who could become eligible for Medicaid if their states adopted expansion, nearly 1.6 million fall in the Medicaid “coverage gap,” with no path to affordable health coverage.^[8] (See Table 1.) They have incomes below the federal poverty level — too low to qualify for financial help in the ACA marketplaces — yet they don’t qualify for Medicaid because their states have not adopted the expansion. In non-expansion states, the median Medicaid income eligibility limit for parents is just 34 percent of the FPL (around $9,000 for a family of three).^[9] And adults without children are generally ineligible for Medicaid on the basis of income, no matter how low their incomes are.

The other 1.2 million uninsured adults who could become eligible for Medicaid expansion have incomes between 100 and 138 percent of the FPL. (See Table 1.) They are currently eligible for premium tax credits (PTCs) for marketplace coverage but are not enrolled.^[10] Of note, this number is based on data from 2024 and has likely risen since, due to the expiration of enhancements to the PTCs.

The PTC enhancements were enacted in 2021 and made marketplace coverage far more affordable and spurred record enrollment, especially for people with incomes between 100 and 138 percent of the FPL in non-expansion states. This group gained access to $0 premium plans with cost-sharing reductions.^[11] In 2025, 6.2 million people with incomes between 100 and 138 percent of the FPL signed up for marketplace coverage in non-expansion states.^[12] However, Congress failed to extend the enhancements, so they expired at the end of 2025. As a result, people with incomes between 100 and 138 percent of the FPL must now pay 2.1 percent of their income for a benchmark plan with cost-sharing reductions. For an individual making $20,000, that’s an annual premium increase from $0 to $420. These premium costs will put coverage out of reach for many low-income families who are struggling to make ends meet and have been relying on $0 premium plans to afford their health coverage.

Without the PTC enhancements, many more adults with incomes between 100 and 138 percent of the FPL will become uninsured in non-expansion states. The Urban Institute projects that the expiration of the enhancements will lead to an additional 3.1 million people dropping marketplace coverage and becoming uninsured in non-expansion states (representing nearly two-thirds of the national increase), with the greatest coverage losses occurring among adults with low incomes.^[13] And those remaining in marketplace coverage are facing much higher costs.

If their states adopt Medicaid expansion, adults with incomes between 100 and 138 percent of the FPL (between around $16,000 and $22,000 for an individual) who are currently enrolled in marketplace coverage would gain access to Medicaid and no longer qualify for marketplace premium tax credits. While people will now have to meet a work requirement (or prove they are exempt) to enroll in coverage through Medicaid expansion, Medicaid has no premiums and generally provides more comprehensive coverage with lower out-of-pocket costs than marketplace plans.^[14]

The expiration of the PTC enhancements makes it even more important that states expand Medicaid. Medicaid expansion would provide adults facing unaffordable premiums and out-of-pocket payments for marketplace coverage, along with adults who remain in the coverage gap, with a path to low-cost, comprehensive coverage.
 

Appendix I: Characteristics of Uninsured Adults Who Could Become Eligible for Medicaid if Their States Adopted Expansion

Appendix II: Data and Methods

We use the Census Bureau’s 2024 American Community Survey (ACS), combined with state Medicaid eligibility rules for 2024, to estimate the expansion-eligible population in the ten states that have not enacted the ACA’s Medicaid expansion. The expansion-eligible population is defined as uninsured adults ages 19-64 with incomes below 138 percent of the FPL and who are ineligible for Medicaid because their states did not adopt the expansion. This includes parents whose incomes are above the parent eligibility limits and adults without children who wouldn’t be eligible at any income level. Uninsured adults with income below 100 percent of the FPL are ineligible for premium tax credits for marketplace coverage and therefore fall into the coverage gap population.^[15]

These estimates do not incorporate the impact of the new Medicaid work requirement. While the work requirement will affect eligibility, most of the reduction in coverage will be among people who should be eligible because they are working or meet an exemption, but who get caught up in the administrative burden of documenting eligibility.

Medicaid and the marketplace have different rules for defining income and family units for the purposes of gaining coverage. These categories of income and family units (known as “health insurance units,” or HIUs) are not directly available in the ACS data and must be estimated. To assess income eligibility, we group individuals into two types of HIUs: Medicaid HIUs and marketplace HIUs. For each type of HIU, we apply each program’s rules for counting modified adjusted gross income for the purposes of eligibility. Our methodology for grouping into HIUs and counting income is based on ACS data and assumptions regarding family relationships, household composition, and tax filing rules and behavior.

Our Medicaid expansion eligibility estimates do not include populations that are already eligible for Medicaid or would not be eligible even if their states expanded. For example, we impute immigration status, broadly following methods used by KFF.^[16] We develop a model predicting lawful immigration status using the second wave of the 2008 Survey of Income and Program Participation. Based on this model, we generate ten statistical imputations in the ACS, controlling to 2023 Center for Migration Studies estimates of the population without a lawful immigration status and estimated undercounts in the ACS.^[17] We do not include the estimated population without a lawful immigration status in our Medicaid expansion eligibility estimates because under existing rules, this group would not gain Medicaid eligibility if their states adopted the expansion.

We define people as having a disability if they meet at least one of the six categories as defined by the Census Bureau: blind or with serious difficulty seeing; deaf or with serious difficulty hearing; serious cognitive difficulty; ambulatory difficulty (i.e., difficulty with a basic physical activity, such as walking or reaching); difficulty with self-care, such as dressing or bathing; or difficulty doing basic activities outside the home alone. We identify people living in rural areas using a crosswalk of Public Use Microdata Areas in the Census to metropolitan statistical areas.^[18]