Crossing the Age-35 Threshold and Overwork: Evidence from China’s migrants

The issue of overwork among migrants has garnered significant attention due to its severe negative impacts. However, existing research has largely overlooked the potential role of age-related labor market barriers. This study exploits the socially salient age-35 threshold in China, where formal and informal hiring rules often make age-35 a focal point in labor-market screening. Using a Sharp Regression Discontinuity Design (RDD) with China Migrants Dynamic Survey (CMDS) data from 2011 to 2018, the age-35 threshold is leveraged as a quasi-natural experiment to identify the relationship between the age-35 threshold and overwork among migrants. We find that crossing the age-35 threshold is significantly associated with an increase in both the probability and intensity of overwork. This association is particularly pronounced among migrants with low human capital, inter-provincial migrants, and “rural-urban” migrants. Mechanism analysis indicates that this effect is linked to three potential pathways: lower monthly income, reduced employment probability, and occupational downgrading. Further analysis reveals that medical insurance may serve to alleviate the overwork tendencies associated with this age cutoff.