The European Union Commission has proposed using consolidated base taxation and formulary apportionment to tax the EU-source income of multinational companies. This paper examines US state experience with a similar approach. Despite some positive lessons, especially the need to consolidate income of affiliated companies, lessons are mostly negative, especially regarding the choice of apportionment formula, the use of economic criteria to define the group whose income is to be consolidated, and complexity caused by lack of uniformity. US experience says nothing about using value added to apportion income—an approach that is conceptually attractive, but subject to transfer pricing problems.