The effect of governmental investment on the effect private investment with the existence of corporate tax

Since investment is one of the effective factors on economical growth and development,paying attention to the growth and development of of investment of pivate parts and the effective factors on on it is important.There is no doubt that the governmental expenses or consumed expenses either in the form of investing expenses of private expenses.governmental investment make the replacement of investment expenses instead of private expenses and governmental expenses have a kind of crowding out but the governmental investment in building high ways,airports and etc has an integral relationship with private investment,and practically there is a crowding in.So in this study the effect of governmental investment on private investment is studid.
They were evaluated through a neoclassical investment model and and the effect of explanatory variables on governmental section ,corporate tax ,inflation,interest rate and two dummy varibles using the econometrics metoth GMM and softwere Eviews for the economy of Iran were assessed. The investment in governmental section ,corporate tax, inflation and interest rate had a negative relationship with private investment but facilities, Adjustment policies and Currency Reserve Fund had positive effects on private investment.Regarding the reversed relationship between investment and corporate tax,applying tax exemption in corporate tax discussion,setting the rate of depreciation more than the real economical deprecation rate,speeding up the acceptable deprciationusing the rate of decresing tax on companies,after several increasing rate and on the whole reassessment of that descrease interest rate can be effective in encouraging investment.