This paper is to study the optimal monetary and fiscal policy in overlapping generations models with Cash-in-advance constraints. By help of the intertemporal equilibrium, the decentralization the optimal growth path is considered by using available policy instruments (i.e, taxes on wages, taxes on capital, public debt and the creation of money).

 The results showed that although the tax rate on capital was always smaller than the ratio of government expenditures to production, but in the special case of Friedman Rule, the two rates were equal to each other. The results revealed that if the government cares equally about all generations, the tax rate on wage will be equal to the ratio of government expenditures to production. To calibrate the model, in addition to the values of the parameters of previous studies, the initial values of variables were used in year 2013. Also, the results of calibrating the model for Iran's economy show that it may take approximately 30 periods for the economy to reach a steady state. However, a comparison between current state and steady state indicates that 8 percent and 32 percent increases in capital per capita and public debt per capita in the steady state.