存在收入差异的社会保障制度选择——基于一个内生增长世代交替模型

社会保障制度选择是经济协调发展中的重要课题。本文建立了一个考虑存在收入差距的异质性个体的内生增长世代交替模型,综合考察了社会保障制度选择对经济增长和收入再分配的影响。分析表明,现收现付制对稳定状态的经济增长率有负面影响,但其收入再分配功能对提高社会总福利存在正向作用,通过数值模拟发现当收入差距较小时,现收现付制对经济增长的抑制作用较强,随着收入差距的拉大,收入再分配功能将逐渐居于主导地位,其综合效应可以改善社会福利。在一定的收入差异程度范围内,存在一个使社会福利最大化的最优现收现付制比率。基于对中国实际的分析,本文认为我国未来的社会保障制度改革应该注重发挥现收现付制的再分配功能。     

存在收入差异的社会保障制度选择--基于一个内生增长世代交替模型

社会保障制度选择是经济协调发展中的重要课题.本文建立了一个考虑存在收入差距的异质性个体的内生增长世代交替模型,综合考察了社会保障制度选择对经济增长和收入再分配的影响.分析表明,现收现付制对稳定状态的经济增长率有负面影响,但其收入再分配功能对提高社会总福利存在正向作用,通过数值模拟发现当收入差距较小时,现收现付制对经济增长的抑制作用较强,随着收入差距的拉大,收入再分配功能将逐渐居于主导地位,其综合效应可以改善社会福利.在一定的收入差异程度范围内,存在一个使社会福利最大化的最优现收现付制比率.基于对中国实际的分析,本文认为我国未来的社会保障制度改革应该注重发挥现收现付制的再分配功能.     

不同生育率情形下养老保险筹资模式比较研究

理论研究普遍认为,基金制养老保险筹资模式优于现收现付制,但这几乎都是基于人均资本视角的判断。本文在外生和内生生育率两种情形下,从福利经济学视角分析基金制是否完全优于现收现付制。理论模型表明,在一定参数组合下,无论外生生育率还是内生生育率,都存在使现收现付制下社会福利高于基金制下社会福利的养老保险缴费率。模型的数值模拟显示,存在使现收现付制下社会福利更高的养老保险缴费率,且在外生生育率下（符合我国生育政策）现收现付制缴费率在12%左右社会福利最高,内生生育率下（符合发达国家生育政策）现收现付制缴费率在6%左右社会福利最高。前一数值与已有研究成果观点相近(我国社会统筹部分缴费率应下降到15%左右),后一数值与美国（62%）、日本（77%）等发达国家现收现付制养老保险缴费率相近。稳健性检验显示,只要参数赋值在合理范围内,数值模拟主要结论不变。本文为降低现行我国社会统筹部分养老保险缴费率提供了理论借鉴。     

遗产税、民生财政与中国经济结构转型

文章运用拓展的迭代模型分析了征收遗产税用于社会保险、教育等民生领域对宏观经济、产业结构和社会福利的影响.研究表明:(1)当遗产税补贴积累型社会保险时为完全中性.(2)在补贴现收现付制社会保险和教育时会减少储蓄、提高老年消费、降低代际财富转移;如果补贴教育或和收入关联的现收现付制,还将推动教育的上升并且前者的影响更大.(3)遗产税收入具有“拉弗曲线特征”.(4)实证检验除证实上述结论外还表明相对于补贴现收现付制,在遗产税收入补贴教育时更有利于实现“稳增长、调结构、促消费”这三个重要的宏观经济管理目标,并大大减少社会福利损失.在存在计划生育时,经济增长率更高,社会福利损失将更小;在生育率内生时,遗产税将推动生育率恢复,但对劳动力供给的影响存在不确定性.     

现收现付制与人口老龄化关系定量分析

中国目前的养老保险和医疗保险实行的是基金积累制为主的筹资模式。按照有关文献的解释 ,这是因为中国正面临着人口迅速老龄化的压力 ,现收现付制不能有效应对人口老龄化 ,而基金积累制则不存在这一问题。本文构造了一个模型 ,详细分析了现收现付制与人口老龄化的关系 ,给出人口老龄化是否导致现收现付制发生支付危机的定量判别条件 ,并根据人口学相关理论和人口资料预测了 2 0 0 1— 2 0 60年中国人口老龄化趋势 ,从而检验了人口老龄化是否引发现收现付制的支付危机 ,同时给出了现收现付制度下养老金缴费率和人均养老金水平增长率的确定原则。     

养老金隐性负债问题浅析

一、养老金隐性负债的成因 长期以来，我国城镇基本养老保险实行的是现收现付制的资金运筹模式。所谓现收现付制是指当期的缴费收入全部用于支付当期的养老金支出开支，不留或留很少的储备基金。从资金角度看，现收现付制的养老保险是一种靠后代养老的保险模式，上一代人没有留下养老储备基金的积累，其养老金全部需要下一代人的缴费筹资，这种保险实际上是代际间的收入转移。     

公共年金制度的效果--运用内生增长模型分析

本文运用导入外部效应的内生增长模型和叠代模型，分析了社会保障制度中不同财政运行方式的年金制度对经济增长率以及社会福利所产生的效果。得出的结论是，不同的年金制度会通过影响个人的生涯可支配收入而对经济增长和社会福利产生不同的影响。由于完全基金方式的年金制度不改变个人的生涯可支配收入，因此具有中性。但是，现收现付的年金制度却有可能改变个人的生涯可支配收入，从而对经济增长率和社会福利产生负面影响。     

“空账”问题引起的思考

所谓基本养老保险空账，指的是由于在现收现付的养老保险模式下职工没有建立个人账户，当从现收现付制向完全积累制或部分积累制转变时，这些人从参加工作到建立新制度这段时间内的个人账户“有名无实”的现象。“空账”运行给我国的养老保险埋下了隐患。这个问题是中国养老保险制度改革中最为紧迫的问题，如不解决，则新旧养老保险制度难以顺利转轨，难以应对人口老龄化对养老金的需求，企业的负担也势必有增无减。本文就如何解决空账问题，谈谈笔者的看法。     

养老保险筹资方式的比较研究

依据筹资机制的不同，各国的养老保险制度大体可归为三大类：一是现收现付式；二是基金式；三是以上两种形式在某种程度上的融合，也称为混合式。在传统计划体制下，中国养老保险制度的特点是现收现付、公共管理、政府完全担保。经过二十几年的市场经济体制改革后，原养老体系得以维系的制度环境已发生很大变化，导致现收现付制难以维系。本文旨在通过对国外成熟的养老保险筹资方式的比较分析，为我国面临重重困境的养老保险体制改革寻求一些切实可行的对策思路。     

中国养老保险制度对城镇居民消费的影响--基于OLG模型和2012年中国省际横截面数据的实证分析

通过建立世代交叠模型探讨我国现行基本养老保险制度对城镇居民消费的影响,指出在现行的现收现付制和完全基金制混合模式下,养老保险对居民消费的影响是有两种不同的效应：人口年龄结构的变化和资金成本的变化。尤其是人口老龄化会改变制度约束从而抑制消费。根据2012年中国省际横截面数据实证分析说明,城镇离退休人员养老金支出对城镇居民消费具有负面影响,说明人口老龄化可能已经开始削弱养老保险制度的社会保障功能。     

Social Security Systems,Human Capital,and Growth in a Small Open Economy

We consider a small open economy in which the level of public education funding is determined by popular vote. We show that growth can be enhanced by the introduction of pay‐as‐you‐go pensions even if the growth rate of aggregate wages falls short of the interest rate. The reason is that the pay‐as‐you‐go (PAYG) system allows future retirees to partially internalize positive externalities of public education due to the positive effect of higher future labor productivity on their pension benefits. The majority support for education funding will be especially strong when the PAYG benefit formula is flat, i.e., progressively redistributive. If a flat benefit PAYG pension system is in place then the economy will achieve the highest growth rate relative to the alternative pension system designs. While such PAYG pension system may be opposed by the majority of working individuals due to inferior returns to their pension contributions relative to a funded scheme, it is likely to be politically sustained by a coalition of older individuals and lower income workers.     

Policy effects on transitional welfare in an overlapping generations model: A pay-as-you-go pension reconsidered

We study the welfare effects of a pay-as-you-go (PAYG) pension system in transition, as well as in the steady state, by showing how the total welfare effects are determined by a cumulative effect on capital. Theoretical studies have shown that the introduction of a PAYG pension system reduces steady-state welfare under dynamic efficiency. Nevertheless, such pension systems have been widely adopted in the real world. To explain this, we algebraically and graphically prove that the PAYG pension system could be Pareto-improving in transition under dynamic efficiency. Similarly, it is acknowledged that this pension system should be introduced under dynamic inefficiency because it improves steady-state welfare. However, we show that the PAYG pension system may be Pareto-deteriorating in transition. Our findings imply that governments adopt PAYG pension systems to achieve policy targets other than long-run welfare maximization.     

Shifting from pay-as-you-go to individual retirement accounts: A path to a sustainable pension system

With aging demographics and generous pension programs, the sustainability of the pay-as-you-go (PAYG) public pension system has been often questioned and has motivated policymakers to enact reforms in many countries. Although mandatory funded Individual Retirement Accounts (IRAs) appear to be a solution to this unsustainable system, existing reforms usually take place within the PAYG system by reducing pension benefits. This paper evaluates the effects of PAYG reforms as well as reforms that switch to the IRA system. Our analysis shows that PAYG reforms outperform IRA reforms in many aspects. In fact, PAYG reforms achieve higher GDP and yield higher welfare in the long run. The transition to the steady state is also found to be less volatile for PAYG reforms. While PAYG generally places a larger burden on future generations, the positive welfare effect of cross-subsidization dominates the welfare loss. Our findings may explain why pension reform is a controversial issue in most countries and why we rarely observe a shift to the IRA system.     

论降低缴费率对养老金给付的影响——基于现收现付制度的视角

在现收现付制中,当前养老金缴费的减少对养老金的给付不一定有消极的影响。由于养老金的给付水平取决于资本份额的分配和跨主观贴现因子,利用简化的戴蒙德的叠代模型证明,当生产资本权重较高和主观贴现因子较低时,当前年轻一代缴费率的减少会提高养老金的给付水平。     

中国传统文化信念、人力资本积累与家庭养老保障机制

本文首先构建一个人力资本积累模型,考察传统文化信念驱动下的家庭养老保障机制以及社会养老保障制度对家庭养老和人力资本投资行为进而对经济增长的影响。分析表明,传统文化信念将后代人力资本积累与父代养老保障有机地联系起来,提供了一种很好的家庭养老保障和人力资本内生积累机制;现收现付型社会养老保障制度不利于人力资本积累和经济增长。其次,本文以我国现实数据为基础进行实证研究,得到结论是社会养老保障制度对我国人力资本积累和经济增长具有明显的抑制作用,而家庭养老保障机制的良好运转则有助于更好地促进人力资本积累和经济增长。因此,我国在致力于完善社会养老保障制度的同时,决不能忽视家庭养老保障机制的作用与培育。     

Increasing PAYG pension benefits and reducing contribution rates

We analyse how a reduced contribution rate affects the balanced pay-as-you-go pension budget in the basic overlapping generations model of neoclassical growth (Diamond, P., 1965. National debt in a neoclassical growth model. American Economic Review 55 (5), 1126–1150). It is shown that PAYG pensions can be increased by reducing the payroll tax paid by the young contributors.     

Optimal social security tax with myopic agents

Myopic agents lack the foresight to save for their own old age. It is generally believed that correcting myopia is a rationale for a pay-as-you-go (PAYG) pension system. This view has been supported by existing literature showing that the optimal PAYG social security tax should increase when people are more myopic. In this paper we obtain new results opposed to the traditional view. By establishing a very standard general equilibrium OLG model with myopic agents and endogenized marginal product of capital, we show that the optimal social security tax should be lower when people are more myopic. Our numerical analysis also shows that the welfare cost of the social security tax increases with people's degree of myopia. These results suggest that correcting myopia is not a clear rationale for the PAYG social security.     

Pension,possible phaseout,and endogenous fertility in general equilibrium

The rich literature on Pay-As-You-Go (PAYG)-type pensions provides a notion that when pension return is dominated by the market return, generally it is impossible to phase pension out without hurting any generation. We show that PAYG pensions can indeed be phased out in a much richer framework where fertility is endogenous and general equilibrium effects are present. Interestingly, the factor that helps us to phase the pension out in a Pareto way is hidden in the structure of PAYG pension itself. Individualistic agents fail to recognize the benefits of their fertility decision on these programs and, therefore, end up in an allocation that is strictly dominated by the allocations that internalize this externality. Exploiting this positive externality, competitive economy can improve its allocations and can reach the planner's steady-state in finite time where each generation secures as much utility as in the competitive equilibrium. Clearly, it is possible to transition in a Pareto way to an economy either with no pension or with pensions whose return is not dominated by market return.     

On myopia as rationale for social security

It has been argued that “paternalistically motivated forced savings constitutes an important, and to some the most important, rationale for social security retirement systems.” This paper revisits the role played by myopia in generating a theoretical rationale for pay-as-you-go (PAYG) social security in dynamically efficient economies. If the competing asset is linear storage and myopic agents are allowed to borrow against future pension benefits, there is no welfare-rationale for PAYG pensions. Sufficiently strong myopia may justify such pensions only if agents cannot borrow against their future pension, but then they are at a zero-saving corner. With enough myopia, co-existence of positive optimal pensions and positive private saving is possible if the return to saving declines with saving, as in a model with a neoclassical technology.