DEFINTION AND TAXATION OF INCOME: NET INCREASE THEORY, RESOURCE THEORY

States want to use the tax instrument, which is one of the most important component of the national sovereignty, in accordance with financial, economical and social policies, to fulfill their basic functions and to serve people composing itself. Tax is a gratuitous, compulsory and monetary share that states collect as a tool of intervention to economic and social life. One of the taxable economic resource within the contemporary tax systems is “income”. Especially in theory, income has been the most accepted subject in taxation, in terms of both ability to pay taxes and to embody structure of economic current. The perspective of taxable income concept appears as the most important element in formation of the income taxation systems. Therefore, the definition of the taxable income has critical importance and this subject brings out debates both in taxation theory and in its practices.