Tax system should be built on two, not contradictory principles. The first one should be the principle of constant efficiency of the tax, which means the adequacy of the tax amount payable and its capability of growing. Constant efficiency is a measure of the assessment of right choices in selecting tax sources. The other principle is the principle of justice in the distribution of tax charges. Tax justice has two aspects: a horizontal and a vertical one. The rule of horizontal justice says that all the subjects in the same economic conditions must be treated in the same manner in respect to tax. At the same time, what is 'unequal' from the tax point of view, must be 'unequally' taxed (vertical justice). Tax justice may be described ...