养老金制度选择与退休行为差异——基于苏州市与苏州工业园区的自然实验数据

The Choices of Pension Insurance Systems and the Differences in Retirement Behaviors——Based on the Natural Experiment Data of Suzhou Industrial Park and Suzhou

本文基于Mitchell&Fields的分析框架,结合苏州市和苏州工业园区养老金制度形成的自然实验,构建反映不同养老金制度下退休行为差异的反事实制度评估模型。采用"边际隐性税率"指标代替"替代率"指标,全面揭示不同养老金制度成本收益;整合精算模型和结构评估模型,并运用退休人员管理数据,验证精算评估结果。研究发现,养老金制度对退休行为的影响因缴费与待遇计发办法的关联规则而异,不同养老金制度对退休行为的激励效应差异巨大,园区退休年龄比苏州市延迟将近两岁。建议通过调整养老金制度模式设计,引导和激励参保职工选择延迟退休。

As the labor force participation rate of the older workers continues to decline, actual retirement age keeps decreasing, the reform of pension insurance system is on the way, One of the most important measures of the reform is the extending of retirement age. Yet how to extend retirement age is still in controversy. The key to solve this problem is to find out the determining factor influencing retirement age. Scholars have studied the effect of individual characteristics on retirement age, including gender, education, nature of work, salary, etc. Recently the trend turns to the effect of institutional factors. The differences of the design theory about equity and efficiency in different pension insurance systems may influence the retirement behavior differently. Suzhou Industrial Park is next to Suzhou, yet their pension insurance systems are totally different. The pension system of Suzhou is partially-fund- ed, in which the social pooling account is under Defined Benefit Plan and the individual account is under Defined Contributions Plan. The more a employee pays, the more benefit he gets. Most of the payment belongs to the poo- ling account. So the system cannot effectively stimulate the workers to retire later. Yet the pension system of Suzhou Industrial Park is central-provident-funded, in which the payment is under Defined Contributions Plan and the ben- efit is under Defined Benefit Plan. The payment belongs to the individual account. So the system is more effective to make the employees retire later. We can see clearly that different pension insurance systems lead to different re- tirement behaviors. In this paper, based on the research of Mitchell and Fields, we construct a eounterfactual system evaluation model and integrate this model with a actuarial model to reflect the differences of the retirement behaviors under dif- ferent pension insurance systems, using the natural experiment produced by the pension insurance systems of Suzhou and Suzhou Industrial Park. Consulting the previous researches, we adopt the marginal implicit tax rate in- dicator instead of replacement rate indicator to reveal the overall cost and income of the pension insurance system. In the evaluation part, we use the retired personnel＇ s management data to verify the actuarial assessment results. What we＇ ve found is that on the whole institutional factors have strong effect on retirement behavior. The in- fluence of different pension insurance systems on retirement behaviors vary with different association rules between payment method and treatment method. With the increasing of months of payment, retirement age under both sys- tems gradually decreases first and then increases again until the months of payment reach a designate value. Also there are great differences in the incentive effects of different pension systems on retirement behaviors. Firstly the months of payment has a stronger effect under the system of the park. Secondly the influences of the monthly aver- age pay cost wage index under two systems are contrary. In details, with this index increasing, the retirement age of Suzhou increases while the retirement age of the Industrial Park decreases. Thirdly, compared with Suzhou, the park＇ s retirement age has been delayed for nearly two years. The differences of retirement age under two systems shows that compared with individual account, social pooling account weakens the contribution of insurance payment to pension benefit, thus makes the workers retire earlier. It is suggested that governors should take institutional factors into consider while changing the pension system. What＇ s more, insured employees should be guided and motivated to postpone the retirement age through the design of pension insurance system, which can relieve the impact on society and economic stability caused by the policy of increasing the legal retirement age directly.