现收现付公共养老金计划收支平衡条件研究——非稳态条件下收入关联制与均等受益制的模拟比较分析

Research on Balance Conditions of PAYG Public Pension Plans:Comparative Analysis between Earning-related System and Flat-benefit System under Non-steady-state Conditions

文章通过连续时间模型分析了收入关联制和均等受益制这两种现收现付制养老金计划的收支平衡条件。结果表明:在面临人口老龄化时,如果替代率保持不变,收入关联制将出现收支失衡;而在一定条件下,均等受益制不会出现收支失衡,但是替代率水平将逐步下降。分析结果还表明,在人口结构变化时,两种计划的替代率都必须以相同的速度下降以维持收支平衡。相对于均等受益制,我国现行的收入关联制基础养老金计划在面临人口老龄化时缺乏替代率调整的政策工具和合理的方式,容易陷入支付危机;而采用均等受益制则有利于维持养老金计划的可持续性,同时保障老年低收入群体的利益。

Through continuous time model, the paper analyzes the balance conditions of two types of PAYG pension plans, namely earning-related system and flat-benefit system. It indicates that, when facing the issue of population aging, the earning-related pension plan will be imbalanced if the substitution ratio keeps constant. However, the flat-benefit pension plan can be sustainable at certain conditions, but the substitution ratio decreases constantly. It also shows that when the population structure changes, the substitution ratios of these two pension plans are required to descend at the same pace in order to avert imbalance. In comparison with flat-benefit system, the earning-related pension plan in China lacks policy instruments and reasonable ways to adjust substitution ratio when facing the issue of population aging, which is apt to result in a payment crisis. Flat-benefit system is helpful to keep the sustainability of pension plans and protect the interests of elderly low-income groups.