Optimal avoidability in cross-border minimum taxation

Many tax regimes collect revenue to the extent that other governments do not. This paper develops a theory of how such cross-border minimum taxes should be designed, focusing on choices that affect avoidance of the regime. Making a minimum tax more difficult to avoid retains more firms within the regime but weakens competition among tax havens. Havens then raise their rates toward the minimum, reducing the top-up tax rate on shifted profit. As a result, an avoidable minimum tax can raise more revenue for the governments that impose it than an unavoidable one.