pagesThis thesis analyzes the tax systems in the EU and role of taxation in the build-up of the EU sovereign debt crisis. According to the assessment made for tax systems in the EU, countries in general have flexible tax systems which can generate revenue. In terms of fairness and equality there are opposite opinions for tax systems of EU countries according to different point of views. As for efficiency there are evidence that tax policies contains inefficient features.Two tax treatments in the EU may have an effect on the build-up of the crisis. These are debt bias taxation of corporations and taxation favoring housing market. These tax treatments made companies and housing market more vulnerable to financial imbalances. On the other hand, some elements and weaknesses of the tax systems in the EU are considered to have adverse effects on the economy prior to the crisis. As a consequence of this examination it is considered that although taxation can not be deemed as one of the causes of the crisis, some tax policies pursued during the precrisis period may have contributed to the causes of the crisis.