Problematyka podstawy opodatkowania dochodu z działalności gospodarczej

The paper is dealing with still essential, though controversial and ones that arouse a number of doubts, problems with settling the basis of taxation in income tax. The subject matter of the paper is limited to the question of the basis of taxation on the incomes from a non-agricultural business conducted by both physical and legal bodies. The author concentrates her considerations basic on three issues which arouse many misunderstanding and doubts in both the doctrine of tax law and in taxation practice: 1) what should be the basis of taxation in income taxes (the term ”basic model”), 2) whether and in what situations the basis of taxation would be defined in a different way, differently than it is presumed by the ”basic model”, 3) what methods are there to settle the basis of taxation and what elements mould the amount of the basis of taxation; the catalogue and principles of tax relief. The three problems are essential in both Polish income taxes. The legal solutions may not always be identical, though they manifest many similarities. The author takes into account both mutual solutions and those specific of both taxes, which deal with the basis of income taxation gained from business by physical and legal bodies.