Abstract: According to a report released by the National Bureau of Statistics in 2020, after the relaxation of the birth policy, the birth rate in China significantly exceeded the average annual level of 16.44 million births during the Twelfth Five-Year Plan period. This undoubtedly affects the choice of the optimal contribution rate for enterprise pension insurance. When calculating the optimal contribution rate for enterprise pension insurance, it is necessary to consider the impact of the multi-child policy in order to improve the accuracy of the research. Although the multi-child policy can to some extent increase the population growth rate in China, it has not fundamentally accelerated population growth. Numerous studies in the academic community unanimously indicate that the relaxation of the birth policy can only slow down the rate at which the population growth rate is declining and cannot stop the trend of declining population growth.
In this article, assuming perfect competition in the market and equilibrium in the capital market, an OLG (Overlapping Generations) model is constructed and solved, taking into account life expectancy and delayed retirement. Furthermore, population growth rates are forecasted in the context of the multi-child policy. Based on research findings from experts and the government, three population growth scenarios are set, and the current optimal contribution rate range for enterprise pension insurance is studied. Moreover, the Fourteenth Five-Year Plan, the 2035 vision, and the research of numerous scholars all indicate that China will implement a policy of delayed retirement in the future. Based on this, two scenarios are set for future retirement age: delaying retirement by 1 year every 3 years and delaying retirement by 1 year every 5 years. The optimal contribution rate for enterprise pension insurance in the future is studied using numerical simulation methods. Finally, a sensitivity analysis is conducted to explore the impact of reducing the contribution rate for enterprise pension insurance and delaying retirement on the economic system. The following conclusions are drawn:
By constructing an OLG model and introducing a social welfare maximization condition, an explicit expression for the contribution rate of enterprise pension insurance is obtained. Numerical simulations reveal that a decrease in the population growth rate will reduce the optimal contribution rate for enterprise pension insurance, while an increase in the population growth rate will raise the optimal contribution rate. Similarly, an increase in life expectancy will raise the optimal contribution rate, while a decrease in life expectancy will lower it. Compared to the elasticities, it is found that life expectancy is the primary factor affecting the contribution rate of enterprise pension insurance. According to the 2019 China Health and Health Development Statistics Report, the life expectancy in China in 2019 was 77.3 years, so the current optimal contribution rate range for enterprise pension insurance is 12.68% to 20.06%.
The National Population Development Plan (2016-2030) predicts that the life expectancy in China will reach 79 years by 2030. If a conservative delayed retirement policy is implemented in the future, the optimal contribution rate for enterprise pension insurance from 2020 to 2030 will be 10.01% to 16.34%. If a moderate delayed retirement policy is implemented, the optimal contribution rate for enterprise pension insurance from 2020 to 2030 will be 7.06% to 13.43%. Therefore, it is recommended that the government control the contribution rate for enterprise pension insurance within the range of 7.06% to 16.34% from 2020 to 2030.
The sensitivity analysis reveals that capital income share, subjective utility discount rate, and social discount factor all significantly impact the optimal contribution rate for enterprise pension insurance. Therefore, the reasonableness of parameter values should be considered. Additionally, reducing the contribution rate for enterprise pension insurance has more benefits than drawbacks. While it may decrease the overall social pension fund, it will increase per capita capital, individual wage income, personal account pension, and savings, thereby enhancing both the consumption during youth and retirement, ultimately improving overall social welfare. Finally, delayed retirement has both advantages and disadvantages for the economic system. Advantages include boosting social pension fund, increasing capital returns, and improving elderly consumption. Disadvantages include reducing per capita capital accumulation, individual wage income, personal account pension, and youth consumption. From a social welfare perspective, delayed retirement may reduce overall social welfare. Therefore, the government should carefully formulate delayed retirement policies while considering leisure and relaxation.

Key words: delayed retirement, pension insurance contribution rate, OLG model

摘要： 基于两期OLG模型,本文综合研究预期寿命、新生育政策以及延迟退休政策对企业养老保险最优缴费率的影响。研究表明预期寿命的延长及人口增长率的提高会导致企业养老保险最优缴费率升高,并且预期寿命对企业养老保险最优缴费率的影响更显著。当前,企业养老保险最优缴费率区间为12.68%~20.06%。但是随着人口预期寿命的提高,叠加大概率会实施的延迟退休政策,2020-2030年企业养老保险最优缴费率区间为7.06%~16.34%,即企业养老保险缴费率未来尚存在一定的降费空间。总的来看,降低企业养老保险缴费率对整个经济系统来说利远大于弊,而延迟退休对整个经济系统来说则是有利有弊,建议政府要在考虑闲暇的基础上审慎地制定和实施延迟退休政策,以改进社会福利。

关键词: 延迟退休, 养老保险缴费率, OLG模型