Claims are special kind of property. They are tangible property, where its owner has limited possibilities of its exploitation. They ae property, which is bailed to another person without compensation. Claims are interest-free commercial credit granted to a debtor. High share of claims in total circulating property can affect negatively on trend of conditions for economic activity. Claims tie sources necessary to acquisition stock needful for production or business activity. In case of irrecoverable claims is possible to reach indirect reduction their evaluation in accounting by way of adjusting items. Claims are the only property, where is creation of adjustment on fulfilment of a condition tax deductible cost. On the limiation of claim do not arise obligation for creditor to eliminate claim from the property. Creditor can willingly decide of elimination of claim anytime. On fulfilment of conditions fixed in the Income Tax Act is junk value of claim tax deductible. When the lawful conditions are not fulfiled, in the case of claim retirement is not the cost incurred by the write-off tax deductible. Here is also the possibility to transfer a debt to another person. In this way is danger of default of payment eliminated. Achievement of claim settlement is also possible by inclusion mutual claims between creditor and debtor.

After accession to the European Union, tax issues acquired and are still acquiring an entirely new character. A new legal environment is forming both in the Czech Republic and in the European Union. Until now, only indirect taxes have been harmonised, with direct taxes having remained in the domain of each member state. However, we are now feeling pressure to harmonise this area as well. Cases concerning value added tax belong to those that are now most often being resolved in front of the European Court of Justice in Luxembourg. Cases regarding direct taxes are also becoming increasingly important. Will direct taxes be harmonized to the same extent as indirect taxes have? When potential investor is considering his investment into a company, he needs to match comparable figures. Definitely, one of the most important criterions is the amount of profit after taxation followed by payout of dividends. If there are different ways of taxation of corporations in various EU Member States, then there would be no possibility to compare corporations placed in various EU Member States objectively. Therefore, the aim of this thesis is, based on the research in the whole EU regarding taxation of corporations, to suggest a method how to harmonize taxation of corporations, which now prevents companies from trading in a single EU market, and also to minimize corporation’s costs of fulfilment of tax administration requirements of each Member State. This aim has been achieved through the following partial aims: .. An analysis of taxation of corporations in each of all 27 EU Member States, .. An analysis of proposals of the European Commission regarding harmonisation of taxation of companies, .. Suggestion of own method of harmonization of taxation of corporations in the EU. In conclusion, there are emphasized the contributions of this thesis to the science, to the practice and to education.