The subject of this thesis is the interpretation of tax legislation, particularly the use ofpreparatory works. The purpose of the thesis is to devise appropriate principles for theinterpretation of tax legislation in general and principles for the use of preparatoryworks in particular. The author discusses the different goals involved in interpreting tax legislation, such as achieving predictability, uniformity and facilitating reasonable courtdecisions. In this context, the effect. of the EC-membership on the use of Swedishpreparatory works in the interpretation of tax legislation is analysed. Subsequently, the use of preparatory works in the interpretation of tax legislationin the Swedish Supreme Administrative Court is examined, from the viewpoint of thegoals for the interpretation of tax legislation. Thereafter, the author discusses German doctrine on the sources of law and theuse of preparatory works in the highest German court of law for tax cases (Bundes-finanzhof). The focus is put on the question of whether any of the distinctive featuresof the German doctrine on the sources of law could contribute toattaining the goals ofthe interpretation of Swedish tax legislation. In the last chapter, the prerequisites of putting forward principles for theinterpretation of tax legislation are discussed and a proposal for an overall structurefor the interpretation of tax legislation is presented. This structure is based on analysisat two different levels. The first level consists of a prima facie analysis of basicprinciples governing the interpretation of tax legislation. The result of the prima facieanalysis is supplemented and tested against the goals of the interpretation of taxlegislation. / <p>Avhandlingen försvarad vid Uppsala universitet.</p>