The trade-off between coverage and benefit: spatiotemporal variation of China’s health insurance and its influencing factors

Achieving universal health coverage has become a global priority, yet internal regional inequalities remain a major challenge within health systems worldwide. China has achieved universal health insurance coverage; however, substantial inequalities persist across provinces, shaped by decentralized welfare governance and uneven socioeconomic development. Existing research has primarily examined urban–rural and population-based inequities, but comprehensive national-level evidence on regional disparities remains limited, particularly since UHC was achieved. This study investigates the spatiotemporal variation of China’s health insurance development and identifies the structural factors driving inter-regional differences. Macro-panel data were collected from official statistical yearbooks. The entropy weight method was used to construct development indices, and the Dagum-Gini coefficient decomposition method was applied to analyze sources of regional disparities. Ward hierarchical clustering was used to identify provincial distribution patterns of coverage and benefit. Fixed-effects ordinary least squares models were employed to examine influencing factors. Despite overall developmental progress, substantial and widening inter-regional disparities persist, primarily driven by divergence between eastern and central/western provinces. Most provinces achieved full or broad coverage with moderate benefit, whereas economically developed eastern provinces showed high benefit but lower coverage, indicating a coverage–benefit trade-off. Under the hukou-based eligibility system, population inflow significantly reduced local coverage rates. Benefit expenditure was positively correlated with fiscal capacity and ageing-related risk structure, while inter-provincial competition significantly shaped benefit generosity, particularly in developed regions. Regional disparities in China’s health insurance system remain substantial. Rather than a deliberate strategic trade-off, these disparities reflect a structural polarization driven by decentralized governance. Population mobility strongly affects coverage, while benefit levels are determined by fiscal capacity, demographic risk structure, and governance competition effects. Policy efforts should focus on eliminating hukou-based restrictions, enhancing portability for migrant populations, strengthening equalization transfers, and developing nationally standardized benefit packages to promote equitable progress toward UHC.