The application of Art. 87(1) EC to taxes above all is connected to the application of the derogation method, which appears to be part of the selectivity criterion. This dissertation examines the application of the derogation method and the assessment of the selectivity criterion applied to taxes, primarily de lege lata, but also de lege ferenda. It begins with an analysis of the relationship among the criteria of Article 87(1) EC and continues with an analysis of the relationship between the derogation method and the assessment of the selectivity criterion applied to taxes. Several scholars have criticised the application of the derogation method because of the difficulty of identifying a derogation and of establishing the benchmark against which the derogation should be assessed. In this dissertation both the benchmark and the establishment of a derogation is analysed, partly with reference to the tax expenditure debate that occurred in the subject area of international taxation during the 1970s and 1980s. The selectivity criterion applied to taxes contains an assessment of justification, whereby the selective nature of a measure can be justified on the basis of the nature or general scheme of the system: Therfore the meaning and implications of this assessment are also examined. After all these issues have been examined de lege lata, the extents to which the application of the derogation method and the assessment of the selectivity criterion follow a logical system are discussed and recommendations for eliminating the identified deficiences are put forward.