本研究旨在探討預期壽命水準對於國民年金保險費率的影響程度。本研究採用龐寶宏（民88）的研究方法，以勞工保險被保險人的資料為樣本，對於國民年金保險費率進行精算評估，在自給自足原則及應計基礎下，亦即在完全提撥制下，針對預期壽命水準高推計、中推計及抵推計等三種死亡率表，試算在折現率（預定年利率）、預定投保薪資年增率以及預定年金額調整率之各種不同組合情況下的費率。研究結果顯示：(1)相較於預期壽命水準中推計的國民年金保險費率，預期壽命水準高推計的費率其高估的程度約為3%至6%，平均的高估程度約為5%，且高估的程度並不隨著預定年利率、預定投保薪資年增率及預定年金額調整率等主要精算變數的變動而明顯不同；(2)相較於預期壽命水準中推計的國民年金保險費率，預期壽命水準抵推計的費率其低估的程度約為10%至16%，平均的低估程度約為13%，且低估的程度亦不隨著預定年利率、預定投保薪資年增率及預定年金額調整率等主要精算變數的變動而明顯不同。換言之，在國民年金保險制度其他修件不變的情況下，由於預期壽命水準的三種不同假設而對國民年金保險費率評估水準的影響程度，約在高估5%至低估13%之間。本研究之結論對國民年金保險制度之費率制定的涵義在於，就合理的費率而言，其受被保險人預期壽命水準影響之程度的可能範圍，約為正負9個百分點；亦即在各項主要的精算變數中，被保險人「預期壽命水準」此一因素變動，相較於反映未來國民年金基金投資報酬率之「折現率或（預定年利率）」及「預定年金額調整率」等因素之可能變動，其重要性或影響程度相對較低。

　　　　　This research is to explore the possible impact of life expectancy on premium rate of national annuity insurance. I adopt the methodology of Pang (1999) to actuarially estimate the insurance premium rate of national annuity insurance from the sample of Labor insurance insured workers. Under the fully self-compensated assumption, i.e. the full funding system, the possible combinations of discounted rate, the expected growth rate of salary, the adjustment rate of annuity are estimated varying from high, medium, and low mortality rate. The results show that (1) the insurance premium rate of high life expectancy is overestimated by 3% to 6%, an average of 5%, as compared with that derived from medium life expectancy. The level of overestimation is fixed with the variance of the actuarial assumption of expected annual rate, the growth rate of salary, and adjustment rate of annuity; (2) the insurance premium rate of low life expectancy is underestimated by 10% to 16%, an average of 13%, as compared with that derived from medium life expectancy. The level of underestimation is also fixed with variance of actuarial assumption. With different assumptions of life expectancy, the deviation of national annuity insurance premium is around the range of positive 5% to negative 13%.