由於光復以來生育率持續下跌，臺灣地區的人口乃於二十世紀末開始迅速老化， 使得老年人的「家庭資源」相應大幅減少，以老年年金給付與一般性醫療保險為主的社會安 全制度已有迫切的需要，本文試圖對於老年年金制度提出具體的構想與數據，希望能對於此 一問題有更深切的了解。我們所構想的老年年金制度是以社會保險為手段，目標在於維持老 年的基本生活，並配合人口結構變遷的中長期財務均衡原則作為發展本土制度的基礎。若以 全體工作人口的基本所得為財務來源，給付對象為全體 65 歲以上的老年公民，以 30 ％的 基本所得替代率為給付水準，在中推計的人口結構條件下，利用目前家庭養老為延遲給付的 措施，則費率將由 5.15 ％以每年 0.52 個百分點的速度上升至 2095 年後維持在 15 ％左 右的水準；如果採行立即給付方式，啟始費率則為 9.09 ％。 而如果準備金能夠以 2 ％的 實質利率孳息，則可使得費率在前三十年至四十年的期間內維持穩定。我們使用人口學慣用 的高、中與低三組人口推計，進一步說明未來人口變遷對於老年年金制度的影響。高推計下 的老年年金費率將上漲至 20 ％，低推計則為 13 ％，顯然生育率愈低的情況則費率上漲的 幅度愈大，財政危機也愈大；而愈靠近替換水準則費率波動愈小，財政問題也愈小。

　　　　　The population transition in Taiwan has been reaching the final phase that the population aging will be phenomenal during the first quarter of the next centry, due to a hastened decline of fertility since 1980. Given the expected upsurge in the aging of population, and consequently the depletion of family support resources for the elderly, it appears only appropriate that Taiwan is seeking to build a social security system including national pension and health insurance programs. This paper explores the effects of population change on the fiscal balance of some hypothetical national pension programs, providing a framework for the investigation of the dynamics involving individual contribution to and benefit from the programs. Two scenarios have been constructed to reflect the ongoing debates on the national pension program: the first one a partially funded (saving) program and the second more inclined to pay-as-you-go. It is shown that given a benefit fixed on 30% of the average basic income, if the population should stabillize at a constant age structure in the long run, the partially funded program entails a lower rate of premium but faster increase in the premium. Based on the comparison of three series of projected-hypothetical populations, the effect of pupulation change on the fiscal balance is further studied. It is demonstrated that the rate of premium directly reflects the fertility level when the population reaches stability. The closer the final fertlity level approaches the replacement level, the lower the rate of premium can be sustained.