偿付能力、生命周期与养老金动态调整策略

Solvency, the Life Cycle, and the Dynamic Adjustment Mechanism of Pensions

本文从生命周期的角度,把养老保险基金的偿付能力作为内生变量,直接引入到养老金调整模型,使之能够自我反馈信息和修正预测偏差,并能根据偿付能力的变化对养老金进行动态调整,最终使养老保障能力与偿付能力实现了内在统一。情景分析表明:(1)在人口出生率和经济增速持续放缓的趋势下,如果不优化当前的养老金调整模式,偿付能力不足的程度将持续加剧;(2)与现行政策和现有模型相比,基于偿付能力构建的调整模型,能有效缓解偿付能力不足的程度,而且降低了养老金大幅波动的风险;(3)结合生命周期理论来调整养老金,不仅偿付能力的提升效果优于其它模式,而且延长了参保人员应对风险的时间,更加符合风险承受能力变化的生命周期特征,提高了抵抗风险的能力;(4)在制定延迟退休年龄等政策时,要综合考虑调整模式、养老金增长率和人口出生率等多方面因素,养老保险基金才可能持久地保持充足的偿付能力。

Population aging and the slowdown of economic growth are challenging the solvency of pension funds.To maintain a sustainable pension system and coordinate the solvency of the pension funds and benefits for retirees,it is necessary to optimize the current adjustment mechanism for pension payments.On the one hand,if the funds have insufficient solvency,pension systems will be unsustainable.On the other hand,if the solvency is increased by simply reducing the benefits,the retirees will be unable to maintain a basic standard of living. We directly use solvency as an endogenous variable and add it to the pension adjustment model,so that the pension payments dynamically adjust to the changes in solvency.When a pension fund is insolvent,the growth rate of the pension payments is automatically reduced.Based on this idea,we construct four pension adjustment modes.The first mode is the current policy,the second mode only adjusts the growth rate of payments during the retirement period,the third mode only adjusts the contribution index during the working period,and the fourth mode adjusts both the growth rate of payments and the contribution index.The payments of the latter three modes are dynamically and automatically adjusted according to the change in solvency,and the modes operate as self - feedback systems that can correct the prediction bias. Solvency is the key index in this paper,and is equal to the ratio of assets to liabilities of a pension fund over some future period.The index needs to be evaluated each year and is used to adjust the pension amounts. When the assets are less than the liabilities,the pension funds are insolvent.Thus,a reasonable level of solvency should be maintained.If the solvency is too high,the contributions will be used inefficiently,as a large proportion will not be used to pay pensions.Therefore,a reasonable adjustment strategy should strive to make the solvency index tend to 1,which will not only maintain the financial sustainability of the fund,but also provide retirees with the greatest degree of security. To determine the assets,liabilities,and solvency of pension funds,we need to calculate the income and expenditure,which means we have to forecast the future values of some parameters,such as the GDP growth rate,birth rate,inflation rate,and life expectancy.The data for 2016 and before are drawn from the National Bureau of Statistics of China.After 2016,we use the"2017 Revision of World Population Prospects"published by the United Nations Population Office,which provides population forecasts for 2017 - 2100.We collect the GDP grow rate data for 2017 - 2100 from the Pardee Center for International Futures at Denver University. As we do not know the exact future values of the parameters,we use the scenario analysis method to test the robustness of the model,which is widely used in the banking and insurance industry.We choose 18 scenarios after analyzing the economic,population,and policy variables.We then analyze,compare,and rank the effects of the four adjustment modes under each scenario,and test whether the ranking is robust.Finally, we identify the most advantageous mode. The main conclusions are as follows.First,if the current pension adjustment mode is not optimized,the degree of insolvency will continue to increase under the trend of population aging and slowing economic growth. Second,compared with the current policies and existing models,our adjustment model can effectively alleviate the degree of insolvency and reduce the large fluctuations in the benefits for retirees.Third,adjusting the pension according to life cycle theory not only improves the solvency better than the other models,but also extends the time for paying retirees and improves their ability to deal with risks.Finally,when introducing policies such as delaying the retirement age,multiple factors need to be considered,such as the adjustment mode,growth rate of pensions,the birth rate,and the solvency of pension funds. This paper makes the following contributions.First,we use solvency as an endogenous variable and add it to the"pay - as - you - go"pension system,whereas the current automatic balance mechanism ( ABM) is applicable only to a fully funded pension system.Second,our model is a self - feedback system that can correct the prediction bias,which improves the robustness and operability of the model.If there is no forecast,the solvency of the pension fund cannot be calculated,whereas if there is no correction,the forecast deviation will continue to increase.Third,compared with other models,such as the ABM,our model can reduce the risk of excessive fluctuations of benefits and provide a more stable income for retirees,although it does require some public financial support.The dynamic effect of public financial support on the solvency of the pension fund is a topic for future research.