The aim of the study is to provide information on the consequences that the adoption of a Common Corporate Tax Base (CCTB) would have on the size of the corporate tax bases of EU companies located in each of the 27 Member States, using the model of the “European Tax Analyzer”. The CCTB as a policy option would replace the current 27 different tax codes for the calculation of taxable income across EU Member States by a single and common set of tax rules. The study shall evaluate the impact on the size of the EU companies’ tax bases of moving from the national corporate tax systems to alternative options for a CCTB, i.e. to an EU-wide harmonization of selected non-consolidation related major provisions of the corporate tax base.