Health insurance portability and coverage: Evidence from China's cross-regional instant reimbursement reform.

Equitable healthcare access for mobile, informally employed populations remains elusive in many developing contexts. We examine the impact of the first phase of China's cross-regional instant reimbursement (CRIR) reform-a province-level reform-on enrollment in health insurance and healthcare utilization. Informed by a theoretical model, we implement a triple-differences design leveraging CRIR's staggered rollout to identify causal effects. Results show that CRIR substantially increased local UEBMI enrollment (by 8%) and healthcare visits (by 14%), while reducing out-of-pocket spending (by 22%). These gains stem from lower administrative frictions and strengthened financial protection. Low-income, less-educated, and more informally employed migrants benefit the most, underscoring the reform's role in promoting inclusive development. Our findings highlight the importance of portable social insurance in improving healthcare access for mobile populations and offer insights for similar reforms in other developing settings.