Changes to ACA Individual Insurance Markets After States Leave Healthcare.gov 2016-2023.

To evaluate changes in enrollment, average risk scores, and premiums in the Affordable Care Act individual market after states transitioned from the federally facilitated marketplace (Healthcare.gov) to a state-based marketplace (SBM) between 2018 and 2023. This study employed a retrospective, quasi-experimental design of secondary data using a synthetic difference-in-differences analysis methodology. Our primary data source consisted of individual market risk adjustment summaries from 2016 to 2023. We conducted a synthetic difference-in-differences analysis to evaluate changes in enrolled member months, average premium paid, and state average risk scores in the individual health insurance market. Our treatment group comprised 4 states that transitioned from Healthcare.gov to a state-based marketplace between 2018 and 2023. The comparison group was the 33 states that continuously used Healthcare.gov from 2016 to 2023. States that converted from the FFM, Healthcare.gov, to a state-based marketplace did not experience statistically significant changes in enrollment, premiums paid, or state average risk scores. These results were robust to alternative specifications. The transition to state-based marketplaces in 4 states did not lead to significant changes in the ACA individual market risk pool enrollment, or premiums paid while potentially increasing state policy autonomy. Future policy efforts should explore how states can leverage policy autonomy to improve market outcomes and coverage.