Estimated Plan Enrollment Outcomes After Changes to US Health Insurance Marketplace Automatic Renewal Rules.

Importance: The American Rescue Plan increases premium subsidies for health insurance marketplace enrollees, potentially leading to situations in which enrollees could switch to other health care plans with lower premiums and less cost sharing (ie, deductibles and copayments). Current policy defaults enrollees to their current health care plan if they automatically renew their coverage, which may cause them to stay in health care plans that, because of the American Rescue Plan, are now dominated in that they have higher premiums and cost sharing than other options. Objective: To estimate the extent to which a smart default policy could reduce US health insurance marketplace enrollees' cost sharing and premiums. Design Setting and Participants: Using 2018 individual enrollment data and 2021 premium data from California's marketplace and the American Rescue Plan premium tax credit subsidy schedule, this economic analysis estimated the characteristics of enrollees' default health care plans if they defaulted into 2021 health care plans under current and smart default policies. The analysis was conducted from March 20 to April 8, 2021. Main Outcomes and Measures: Characteristics of enrollees' default health care plans under current and smart default policies, including net premiums, plan levels, and cost sharing. Results: The analytic sample consisted of 748 087 Covered California enrollees from 2018 (mean [SD] age, 44.80 [13.72] years; 408 410 [54.6%] women). Under current policy with the enhanced subsidies implemented under the American Rescue Plan, 5.8% of sample enrollees would default into dominated health plans. Of these enrollees, 98.0% would have incomes below 250% of the federal poverty level. A smart default policy would lead to a mean $102.47 decrease in monthly premiums (95% CI, $103.84-$101.10), a mean $1960 reduction in individual annual medical deductibles (95% CI, $1991-$1928), and a $49.56 reduction in specialty prescription copays (95% CI, $49.77-$49.34). Conclusions and Relevance: The findings of this economic analysis suggest that a smart default policy could avoid defaulting lower-income marketplace enrollees to objectively inferior health care insurance plans and may lead to large reductions in lower-income enrollees' deductibles, copayments, and maximum out-of-pocket amounts. Implementation of a smart default policy could enable marketplace administrators to reduce the prevalence of underinsurance among lower-income marketplace enrollees.