Turkish Abstract: En onemli siyasal ve ekonomik butunlesme hareketlerinden birisi olan Avrupa Birligi ile olan iliskiler uye olsun olmasin cogu ulkeler icin onem tasimaktadir. Zira bu ulkeler toplulugu onemli bir boyuta ulasmakta ve bu ‘pazar’ ile alisveris yapacak olanlari daha onemli olcude etkileyebilmekte ve ayni zamanda ‘siyasal bir birlik’ olarak dunya siyasetinde giderek daha onemli bir rol oynamaktadir. Dogal olarak ulkemizin tam uye olmasi sansi vardir. Bu durumda tam uyeligin avantajlarindan suratle yararlanmak ve getirebilecegi olumsuz etkilerden hizla siyrilabilmek icin, vergi sistemimizin kisa zamanda Avrupa Birligi standartlari yonunde duzenlenmesi buyuk oneme sahip bulunmaktadir. English Abstract: In this study, tax harmonization aspects of the European Union (EU) are being examined. Financial aspects of a possible integration of Turkey with EU are also covered. With this framework, topic permits to analyze Turkey's accession and harmonization of its tax and financial policies in a context of an enlargement of the Union. Book one is devoted to the presentation of the Union. Here, the harmonization concept explained and its relations the other disciplines being reviewed. Following chapter is describing the EU practices in terms of the theoretical contributions. The reason for such an extensive picture of the real world is the condition imposed by the EU to the new members. All new members have to accept all the existing regulation to date. However such areas in which some exceptions in the transition periods can be obtained by exemplifying the difficulties of the previous enlargements are shown. These transitory periods are generally bound to be limited to a short time. This represents obvious need for Turkey an accelerated period of preparations for accession. Otherwise the transition period would take longer. The EU members, even though are powerful enough to carry the burden of premature accession of Turkey, seem reluctant to assume such a burden. Thus, Turkey is being forced to develop its economy before the full membership. Obviously, the common value added tax (VAT) is the major achievement of the Union. The application of such a tax in Turkey implies many related problems coming to the scene, such as the efforts to diminish the tax fraud or the determination of the relevant economic and financial policies. Turkey before accepting a VAT should consider seriously the analysis of prospective effects of such a tax. Taking into consideration of the fact that there will be no harmonization in personal income taxation within EU, Turkey may decide to intensify the coverage of personal income tax while keeping at low levels the VAT which constitutes one of the components of cost formation. In terms of such an analysis, Turkey's February/l980 VAT draft is bringing a high burden while Income Tax draft can be defined as an insufficient one. Book two analyses the effects of the enlargement of the Union and prospects for the accession of Turkey. Here, Turkey's past relations with the Union is the major area of interest. This part followed by the search for the comparable external relations of the Union. The concessions made by the Union members to the young African nations are in some cases represent higher relative advantages in comparison to the similar concessions made to Turkey, one of the full member candidates. On the other hand, new candidates, Spain and Portugal and new member Greece seem to bring the new problems to the Union-Turkey relations as they are of similar agricultural production patterns. The last chapter is for the review and comments on the Turkey-EU relations. Given the facts that the Agreements of Turkey with EU representing the uncertainty for the major topics and the behavior of the Turkey's governments are also far from being clear about the future of relations with EU, it is observed that the need for preparations of in-depth studies by the expert groups has become obvious. With an ever growing trade volume, Union has already become the major trade partner of Turkey. The harmonization of economic and financial policies, even in the lack of integration of Turkey to EU, is being necessitated merely by this fact. The positive result, it is believed that will only help for an increased welfare of the Turkish people and healthier Turkish economy.