January 2024, Paper: "Health insurance premiums are primarily understood to pose financial barriers to coverage. However, the need to remit monthly premium payments may also create administrative burdens that negatively affect coverage, even in cases where affordability is a negligible concern. Using 2016–17 data from the Massachusetts health insurance Marketplace and a natural experiment, we evaluated how coverage retention was affected by the introduction of nominal (less than $10 for most enrollees) monthly premiums for plans that previously had $0 premiums. Compared with plans that maintained $0 premiums, those that took on nominal premiums saw enrollment fall by 14 percent over the following year. This attrition was attributable to terminations for nonpayment; most terminations occurred at the end of January, implying that a significant number of affected enrollees never initiated premium payments. These findings suggest that even very small premiums act as enrollment barriers, which may sometimes reflect administrative burdens more than financial hardship. Several policy approaches could mitigate adverse coverage outcomes related to nominal premiums."