The Optimal Tax Rate and Efficiency of Government in Selected Lower-Middle and Upper-Middle-Income Countries and Members of the OIC: Stochastic Metafrontier Approach

In the last two decades, some economists have provided a model for obtaining the optimal tax rate to maximize economic growth. Aiming to contribute to these studies, this work presents a new approach for the determination of the optimal tax rate based on a stochastic metafrontier analysis. To this end, the meta technical efficiency (MTE), group’s technical efficiency (TE), technology gap ratio (TGR), and optimal tax rate (OTR) were determined for the period 1996-2018 in a selection of member countries of the Organization of Islamic Cooperation (Group A), lower-middle-income (Group B) and upper-middle-income (Group C). It was found that Group A has the maximum average values of MTE, TE, and TGR, while most countries in Group B have the minimum average MTE. The results demonstrated that Russia enjoys the highest average values of MTE, TE, and TGR, and can be considered as the reference for the countries in Group C. Finally, it was concluded that with 90% statistical confidence, the average real tax rates in Iran and Kuwait are less than the balanced budget OTR during the studied period. The emphasis on increasing tax rates to maximize economic growth and the improvement in the efficiency of these governments seems necessary.