养老保险个人账户“三差损”与计发系数动态调整

Three Differential Losses of Individual Account for Old-age Insurance and Dynamic Adjustment of Annuity Divisor

为全面分析计发系数动态调整对降低企业职工基本养老保险个人账户支付缺口的效果,本文将支付缺口分解为长寿风险引起的“寿差损”、养老保险基金实际收益率低于记账利率引起的“利差损”、投资收益低于养老金调增额引起的“增差损”。研究发现:(1)实际收益率低于记账利率情景下,动态调整计发系数可直接降低寿差损、间接降低增差损和利差损,预测期间个人账户年度支付缺口先增后减,其精算现值下降约52%。(2)调整计发系数的同时若能让基金实际收益率提高至记账利率,则可降低全部“三差损”,使年度支付缺口精算现值下降约75%。虽然同时调整计发系数和调低记账利率可令支付缺口精算现值下降约80%,但会显著降低养老金。(3)分性别计发系数表和中性计发系数表下的支付缺口差别不大,后者的再分配效应可缩小养老金的性别差距。因此,同时动态调整计发系数和提高基金实际收益率是缩小个人账户支付缺口最有效和可行的方法。

Add to Favorite Three Differential Losses of Individual Account for Old-age Insurance and Dynamic Adjustment of Annuity Divisor YANG Zaigui;QIN Shaopeng;China Institute for Actuarial Science,Central University of Finance and Economics;The annuity divisor table for the individual account in China's Basic Old-age Insurance for Enterprise Employees(BOIEE)has not been revised for nearly two decades,which underestimates the benefit payment period.Though China has proposed plan to revise the annuity divisor table,most studies examining the impact of annuity divisor dynamic adjustment only calculated the shortfall resulting from the extension of average life expectancy,without taking into account the shortfall caused by the excessively low actual return rate(ARR)of pension funds.Based on the assumption that the booking interest rate(BIR)is higher than the ARR,this paper decomposes the shortfall of individual account into the“longevity differential loss(LDL)”caused by longevity risk,the“interest differential loss(IDL)”caused by the ARR being lower than the BIR,and the“growth differential loss(GDL)”caused by investment returns being lower than the growth increment of the benefits.Thus,the annual deficit of all participants'individual accounts can be summarized into three parts,namely,the in-service death return gap,the pension payable gap and the inheritance gap.Based on the mortality rates for China predicted in the World Population Prospects 2022 and other assumptions,we have compiled gender-specific and unisex annuity divisor tables that are adjusted every five years.The result indicates that under the scenario where the ARR is lower than the BIR,dynamic adjustment of the annuity divisor can directly reduce LDL,indirectly reduce IDL and GDL.In the annual deficit,the in-service death return gap is not affected by the annuity divisor.Since the new annuity divisor table only applies to retirees after 2025,there is a lag in the decrease of the pension payable gap,and the inheritance gap will continue to increase.Therefore,the annual deficit will first increase and then decrease,with the actuarial present value of the annual deficit predicted to decrease by approximately 52%during the forecast period.If the annuity divisor is adjusted while simultaneously raising the ARR to the BIR,all three losses are reduced.The in-service death return gap can be gradually reduced to zero,and the actuarial present value of the annual deficit decreasing by approximately 75%.Although simultaneously lowering the BIR can decrease the actuarial present value of the annual deficit by approximately 80%,it significantly diminishes participants'pension replacement rate.There is little difference in annual deficit between gender-specific and unisex annuity divisor tables;however,the latter exhibits a redistribution effect that narrows the gender gap in benefits.Thus we recommend that China adopt a dynamically adjusted unisex annuity divisor table in the future while also striving to improve the investment return rate of the BOIEE.