Differentiating between different stages of international cooperation, we first describe the institutional form in the bargaining and agreement stages of cooperation. This description shows that the regimes are quite similar in the bargaining stage, both exhibiting a mix of bilateral and multilateral bargaining. However, while agreement is multilateral in the trade regime it is bilateral in taxation.

Based on stylized institutional histories of both cases we develop simple game theoretic models incorporating domestic level considerations. Building on these models we then go on to explain the institutional choice between bilateral and multilateral cooperation. We show that state concerns for the distribution of benefits can be best achieved under bilateral bargaining in both regimes. However, in order to lower transaction costs there are also elements of multilateral bargaining. Agreement is multilateral in trade in order to overcome a free-rider problem that results from an interaction of concerns for distribution and enforcement. Since such a problem of free-riding does not exist in taxation, there is no need for binding multilateral agreement.