In this research, the effects of fiscal policy on the investment
in active companies of stock exchange in the conditions of financial friction evaluated. For this purpose, the data of ۱۰۵ companies during the period of ۲۰۱۰ to ۲۰۱۸ is used. First, by using the threshold panel model, financial friction conditions were determined based on the non-linear relationship between the debt ratio and Tobin's Q
index. In this regard, we saw three different regimes influencing the debt ratio on Tobin's Q, two regimes of low debt and average debt was statistically significant and had a negative effect, but the third regime was not statistically significant. Also, based on the threshold variable (debt ratio between ۰.۴۸۳۶ and ۰.۶۵۶۵), about ۶۹.۷۲ companies are in the average debt regime. The results of the research showed that the effective tax rate variable (representative of fiscal policy in the model) had a negative and significant effect on the investment
index of companies. Therefore, financial policy has a limiting effect on the investment
of companies. On the other hand, company size indicators have a positive and significant effect and debt ratio index had to the extent that companies operate in financial friction conditions. To the extent that companies operate in financial friction conditions, their access to credit reduced, as a result, the role of tax and debt ratio in influencing investment
respectively, it will be more noticeable and pale.