The purpose of this paper is to assess the selected tax expenditures in German personal income tax aimed to support farmers. German system of tax preferences is undoubtedly one of the most interesting examples of agricultural tax expenditures in the member states of the European Union. The paper is also an attempt to answer the question, whether method applied to estimate agricultural production income in the German personal income tax, in fact, lowers the tax burden of farms owners and, secondly, what are the consequences of this instrument for agriculture sector? The conducted study confirmed that the introduction of this tax expenditure has resulted in a simplification of the tax accountancy obligations of farmers. However, at the same time due to the reduction of the fiscal burden, there is significant inhibition of transformation of the area structure of farms in Germany.