【摘要】 社会保险制度是优化收入分配格局、促进共同富裕的重要保障。本文先从理论层面考察了企业社会保险缴费负担对劳动收入份额的影响，发现社保缴费负担通过资本和劳动替代（互补）效应、产品市场垄断力量以及劳动力市场垄断力量3种途径影响劳动收入份额。借助2011年《中华人民共和国社会保险法》颁布实施的准自然实验和双重差分法的经验分析，我们发现企业社保缴费负担加重显著地降低了企业劳动收入份额。此外，机制分析结果表明，社保缴费负担提高对劳动收入份额的负面影响主要是由企业在产品市场和劳动力市场的垄断力量提升导致的；制造业、小微企业及低工资企业受到的负面影响更明显，特别是小微企业和低工资企业员工的就业和工资显著下降，表明社保缴费负担增加对低收入群体的负面影响更为突出。本文为进一步完善中国社会保险制度的收入分配职能、促进共同富裕提供了重要参考。更多还原

【Abstract】 The social insurance system plays a crucial role in optimising income redistribution and promoting common prosperity. This paper first examines the impact of corporate social security contributions on the labour income share. The theoretical analysis reveals that social insurance contributions affect the labour income share through three mechanisms: capital-labour substitution(complementarity), monopoly power in the goods market and monopsony power in the labour market.Using the implementation of the 2011 Social Insurance Law as a quasi-natural experiment and employing a difference-in-differences(DID) approach for empirical analysis, a significant reduction in corporate labour income share is observed when corporate social insurance contributions increase. The results of the mechanism analysis indicate that this negative impact is primarily due to increased corporate market power in both the goods and labour markets, which is more pronounced in the manufacturing sector, small and micro firms, and low-wage firms. In particular, employees in small and micro firms, as well as low-wage firms, experience significant declines in employment and wages. This suggests that the negative impact of increasing social insurance contributions is more prominent among low-income labour. The findings of this study provide important insights for further enhancing the income redistribution of China’s social insurance system and promoting common prosperity.更多还原