Should a subset of member states of a federation be allowed to form a sub-union on some policy issue? When centralization is not politically feasible, allowing an enhanced cooperation agreement among a subset of countries permits the latter to gain benefits which would otherwise be lost....

We study the optimal combination of corporate tax rate and tax base in a model of a small open economy with heterogeneous firms. We show that it is optimal for the small country's government to effectively subsidize capital inputs by granting a tax allowance in excess of the true costs of...