The adoption of IAS/IFRS in the European Union is part of the European Commission’s globaltax harmonisation policy whose aim is to establish a common (consolidated) corporate tax base. The paper shows that the impact of an IAS/IFRS- based tax accounting on the effective tax burden of Belgian companies is large and not uniform across sectors. Some sectors, like construction and automotive vehicles, experience much larger increases in effective tax burdens than others. Globally the impact is relatively important. The analysis is conducted thanks to the European Tax Analyzer, a multi-period forward looking program. In a European context, an IAS/IFRS-based tax accounting will increase the effective corporate tax burdens in all selected countries. However it will most probably maintain the current tax competitive positions of EU countries. The expected broadening of the tax base could constitute an opportunity to reduce the corporate income tax rate without changing the overall effective burden. ; info:eu-repo/semantics/published