Medicaid Impact Methodology
A consideration in interpreting these projections is that we do not know the specific health, economic, and other circumstances of those who may lose coverage. The expansion population may be generally healthier and higher income than those categorically eligible, but the added administrative burdens (e.g., work requirements, more frequent redetermination) could disproportionately impact those with worse health, less education, and fewer resources. The actual coverage losses and trajectory of them during the 10-year budget window are an obvious source of uncertainty as well as our reliance on single studies for treatment effect estimates for each outcome. Our goal was to balance responsiveness and rigor, these projections should be interpreted through that lens. Tracking of the impacts of any funding and policy changes that come to pass will be critically important.
Coverage loss
Over 71 million people had Medicaid coverage in the United States as of January 2025.1 We looked at how many people would lose their Medicaid coverage because of proposed changes to eligibility and administrative burdens, like work requirements and frequency of eligibility redetermination, in the One Big Beautiful Bill Act (OBBBA).2 The Congressional Budget Office (CBO) projects that 11.8 million Americans will lose health insurance coverage as a result of the proposed changes over a 10-year period from 2025-2034, but did not explicitly specify how many would be projected to lose Medicaid.3 Manatt estimates that approximately 8.7 million Americans will lose Medicaid coverage, over a 12% drop in enrollment from January 2025 and a 10% reduction from baseline, with the vast majority of the coverage losses coming from the adult expansion population.1,4-5 We use this estimate as the basis for projecting the other outcomes, though there are others.
KFF projects that state-level Medicaid spending cuts will range between 6% (Alabama and Wyoming) up to 21% (Louisiana and Virginia) of 10-year baseline federal spending.6 These estimates do not attempt to predict how states will respond to the federal policy changes, which could buffer against or increase enrollment losses and/or change access and benefits for those still enrolled (e.g., lower provider reimbursements, end optional benefits). Also, coverage losses will accumulate over the 10-year budget window. For our purposes, we did not project year-by-year changes in the subsequent measures and instead projected the number of Americans that would be affected based on the total estimated enrollment loss.
Catastrophic health expenditures
We projected how the proposed changes could affect cost burdens for health care associated with rising uninsurance, also referred to as catastrophic health expenditures, defined as spending more than 30% of family income on health care in a year. We used results from the Oregon Health Insurance Experiment, published in the New England Journal of Medicine, that estimated an 81.4% relative reduction in catastrophic health expenditures due to gaining Medicaid coverage (95% CI: -150.2%, -12.5%).7 Assuming this effect is mirrored in reverse, approximately 7.1 million additional Americans could face catastrophic health expenditures (95% CI: 1.1 million, 13.1 million). People who have catastrophic medical expenditures are much more likely to have significant medical debt. Medical debt is, in turn, the leading cause of personal bankruptcy and can lead to evictions.
Usual source of care
We projected how the proposed changes would impact access to care, specifically having a usual source of care. We used results from the Oregon Health Insurance Experiment, published in the New England Journal of Medicine, that estimated a 51.2% relative increase in having a usual source of care due to gaining Medicaid coverage (95% CI: 33.5%, 69.5%).7 Assuming this effect is mirrored in reverse, approximately 4.5 million additional Americans could lose their usual source of care (95% CI: 2.9 million, 6.0 million).
Mortality
There is strong quasi-experimental evidence on the mortality effects of Medicaid expansion, but less on having Medicaid generally versus being uninsured, so we focused on the former. We projected how the proposed changes would impact mortality, relying on two sources, projecting at least 1,481 to 10,428 additional adult deaths per year nationally.
First, a recent National Bureau of Economic Research working paper estimated that Medicaid expansion saved approximately 3,220 lives per year relative to non-expansion states.8 Relative to a baseline of 15 million expansion adults enrolled,9 Manatt projects that a majority of the adult coverage losses will be among expansion adults,5 approximately 6.9 million, which implies that 46% of them will lose coverage. Applied proportionally, this suggests that we can expect an additional 1,481 deaths per year just among the expansion adult population. This does not include mortality among adults enrolled through traditional eligibility categories that may lose coverage, who are likely to be older and less healthy and therefore have higher mortality benefit from Medicaid coverage, so these estimates are likely conservative. Second, we used a Lancet Public Health study that quantified mortality effects of Medicaid expansions at a population level, estimating that expansion led to a 11.8 per 100,000 adults aged 25-64 reduction in annual state-level all-cause mortality.10 As July 2024, the 41 states (including DC) that have adopted Medicaid expansion comprise over 192 million (192,119,123) in adult population according to the US Census Bureau.11 Applying the rate above with the expected proportional coverage loss (46%), this suggests that we can expect an additional 10,428 deaths per year among adults in expansion states. This does not include mortality among adults in the remaining ten non-expansion states or those enrolled through traditional eligibility categories that may lose coverage, so these estimates may also be conservative, but may also could be an overestimate given its measurement of mortality effects among all adults, not just those on Medicaid.
Estimation review
This and prior versions of these estimates were developed and/or reviewed (in alphabetical order) by Nahid Bhadelia (BU), Jacob Bor (BU), Charlotte Bruce (BMC), Jennifer Dodge (USC), Stephanie Ettinger de Cuba (BU, BMC), Brooke Nichols (BU), Brian Lee (USC), Paul Shafer (BU), and Justin White (BU).