When a group of affiliated corporations have the option to file a single tax return based on a combined income, what types of groups would take up the option? This study empirically analyses decisions to participate in a single-jurisdiction consolidated tax filing. The data consists of 2,782 Japanese corporate groups headed by publicly-traded corporations observed over 2002-2007. Results indicate higher likelihood of participation among groups characterised by low correlation in returns among group members, high variance in returns, large number of subsidiaries, and losses accumulated in parents. The significant influence of variance and covariance of returns suggests that a consolidation scheme improves the efficiency of corporate income tax through reducing profit shifting.