Since its passage in 2010, the Affordable Care Act (ACA) has helped reduce the uninsured rate to record lows, but changes in insurance coverage over time, known as churn, remain a concern. A recent survey found that nearly 25 percent of respondents reported a change in coverage over the previous twelve months. Among the most common reasons for churn is the loss of Medicaid eligibility, placing low-income populations at risk of a coverage gap. To date, little evidence exists on effective strategies states can use to facilitate Medicaid to Marketplace coverage transitions, an issue that has become more pressing amid projections that upwards of 15 million people could lose Medicaid eligibility once the COVID-19 public health emergency expires.

To address this gap and to inform Marketplace administrators, during a Special Enrollment Period (SEP) in 2017 in California's ACA Marketplace, we conducted a randomized controlled trial to examine the effect of email reminders, personalized telephone outreach, as well as the combination of the two forms of outreach on ACA enrollment among households who recently lost Medicaid and became eligible for subsidized Marketplace coverage.

During the SEP at the end of August 2017, the investigators randomly assigned households to one of four arms based on the last digit of their household identifier: a control group assigned to receive no outreach beyond an initial eligibility determination notice; an email-only group assigned to receive an initial eligibility determination plus email reminders about signing up for marketplace coverage; a phone-only group assigned to receive an initial eligibility determination plus a phone call offering enrollment assistance from a service center representative (SCR); a phone + email group assigned to receive an initial eligibility determination, email reminders about signing up for marketplace coverage and a phone call offering enrollment assistance.

Inclusion Criteria:

• Those who recently lost Medicaid eligibility and became eligible for subsidized Affordable Care Act coverage

Exclusion Criteria:

• Those who recently lost Medicaid eligibility and were found ineligible for subsidies.

The researchers are committed to sharing as much data as possible for replication, consistent with the privacy and security requirements of the state agency that govern the re-disclosure of the data.

Data will be available with investigator support upon publication.

Replication data can be accessed via request to the primary investigator upon publication.