Abstract: Improving the social security system is an important way to improve income distribution and achieve common prosperity. With the monthly panel data of Shanghai enterprises, this paper uses the process optimization reform on social insurance declaration and payment as a shock to investigate the impact of increasing levy intensity on small and micro enterprises' social insurance contribution and fee-shifting through wages. It is found that, compared with medium and large enterprises, the social security increasing levy intensity significantly improves the small and micro enterprises' social insurance contribution. However, the wage levels of employees in these enterprises experience a notable decline. The above conclusions are still valid after a series of robustness tests such as the parallel trend test and placebo test. The results of the heterogeneity analysis show that the normative effect of increasing levy intensity on small and micro enterprises' social insurance contribution and the fee-shifting effect through wages are particularly obvious in small and micro enterprises in the service industry and with weak wage rigid constraints. Finally, it is necessary to continuously lower the social security rate, implement targeted tax reduction and exemption policies, and reform the social security contribution base to reduce the system threshold for low-income groups.

Key words: Collection System, Social Insurance Contribution, Small and Micro Enterprises, Tax Incidence

摘要： 健全社会保障制度是改善收入分配、实现共同富裕的重要途径。本文基于社会保险费申报缴纳流程优化改革这一政策冲击,利用上海市企业月度面板数据考察了征管强度提升对小微企业社保缴费及工资转嫁的影响。研究发现,相对于中大型企业,征管强度提升显著提高了小微企业的社保缴费规范性,但小微企业员工的工资水平显著下降。以上结论经过平行趋势检验、安慰剂检验等一系列稳健性检验后仍然成立。异质性分析结果表明,征管强度提升对社保缴费的规范作用以及工资转嫁效应在服务业、工资刚性约束弱的小微企业表现得尤为明显。基于研究发现,本文提出持续降低社保费率、实行针对性税费减免政策以及进行社保缴费基数改革以降低低收入群体参保的制度门槛等政策建议。

关键词: 征管体制, 社保缴费, 小微企业, 税费转嫁