Under the same umbrella: Public health insurance expansions and the uniformity of insurance for families

Evaluating insurance coverage at the individual level abstracts away from the family-level decision-making behind healthcare utilization. While traditional private insurance tends to be offered to either adult individuals or whole families, public insurance eligibility historically has been determined person-by-person. Income eligibility thresholds for public coverage can differ for parents and children, even among children in different age groups. Having different insurance sources or a mix of insured and uninsured family members may disrupt consistent medical care. In this paper, we examine the relationship between changes in eligibility thresholds for adults and children and the resulting mismatched insurance coverage patterns. Using the Current Population Survey, we document patterns of insurance mismatch over time, showing that despite some recovery following Medicaid expansion, the uniformity of insurance coverage has declined by nearly 10 percentage points in the past 30 years for families below 400% of the poverty line. We find that expansions of parental Medicaid income thresholds can promote uniform insurance coverage for families, whereas child expansions of Medicaid or the Children’s Health Insurance Program have a negligible effect on uniformity. Parental results are driven by families led by single mothers, who are more likely to be affected by Medicaid expansions for parents. Treating a family as the main observation unit provides important insights and details the potential unintended consequences of individual-level public insurance policy.