The existence of tax concessions (tax exemption, tax holiday, allowances …) provide the possibility of reducing tax liability via special tax provisions or regulations in tax laws  for some taxpayers, hence government loses  some tax revenues. Therefore, the forgone tax revenues resulting from some of the tax concessions for particular taxpayers, regions and sectors of an economy, are considered as tax expenditures. However, tax expenditures can be considered as a policy instrument for achieving the special economic goals, but do not appear in a regular budget and impose a lot of financial pressure on it.  In the recent decade, this reason causes tax expenditures are estimated and reported in a number of countries. The findings of the present study, which are derived from descriptive-analytic method with emphasis on comparative comparisons of tax expenditures in selected countries, indicate that in all of them, tax expenditures are studied with the aim to increase financial transparency of government and are calculated by using forgone revenue method. In compiling tax expenditures reports of the most countries tax expenditures are defined as a deviation of a specified benchmark tax system and they are presented independently or in related to the regular budgeting process.