Investigating the effects of demographic change on the financial sustainability of the pension fund using the Overlapping Generation Model based on the DSGE model

This study examines the effects of demographic changes including decreasing fertility and increasing life expectancy and retirement age on the financial sustainability of the pension fund in Iran using the overlapping generation model and the Stochastic Dynamic General Equilibrium (DSGE) approach. The results of simulation and evaluation of impulse response functions and evaluation of correlation coefficients show that there is a positive correlation between the variables of fertility and life expectancy with the financial deficit of the pension fund. With a negative shock in the fertility, the pension fundchr(chr('39')39chr('39'))s deficit reacts negatively and deviates in the negative direction from the long-term equilibrium level and the pension fundchr(chr('39')39chr('39'))s financial stability improves. However, savings, capital stock and output react to this Shocks, negatively. On the other hand, based on the impulse response functions, with the occurrence of a positive shock in life expectancy, the fund deficit reacts positively and deviates from the long-run equilibrium level in a positive direction, and savings, capital stock and production also respond to this shock positively. Also, with a positive shock to working period or increase in retirement age, the fundchr(chr('39')39chr('39'))s financial deficit reacts negatively and deviates from the long-term equilibrium in a negative direction, and savings, capital stock and output also respond positively to this shock. Due to the results, with the increase of positive shock during the working period or increasing the retirement age, the average long-run equilibrium level of the pension fund deficit decreases and financial stability of the pension fund improves. Based on the results, the implementation of the policy of increasing the length of service and increasing the retirement age is recommended as a useful tool for the improving financial sustainability of pension funds in Iran.