Exploring Characteristics and Health Care Utilization Trends Among Individuals Who Fall in the Health Insurance Assistance Gap in a Medicaid Nonexpansion State

States that did not expand Medicaid under the Affordable Care Act (ACA) in the United States have seen a growth in the number of individuals who fall in the assistance gap, defined as having incomes above the Medicaid eligibility limit (≥44% of the federal poverty level) but below the lower limit (<100%) to be eligible for tax credits for premium subsidies or cost-sharing reductions in the marketplace. The purpose of this article is to present findings from a secondary data analysis examining the characteristics of those who fell in the assistance gap ( n = 166) in Missouri, a Medicaid nonexpansion state, by comparing them with those who did not fall in the assistance gap ( n = 157). Participants completed online demographic questionnaires and self-reported measures of health and insurance status, health literacy, numeracy, and health insurance literacy. A select group completed a 1-year follow-up survey about health insurance enrollment and health care utilization. Compared with the nonassistance gap group, individuals in the assistance gap were more likely to have lower levels of education, have at least one chronic condition, be uninsured at baseline, and be seeking health care coverage for additional dependents. Individuals in the assistance gap had significantly lower annual incomes and higher annual premiums when compared with the nonassistance gap group and were less likely to be insured through the marketplace or other private insurance at the 1-year follow-up. Findings provide several practice and policy implications for expanding health insurance coverage, reducing costs, and improving access to care for underserved populations.