The vast majority of countries are WTO members. Arguably the WTO is both the rationale for a "minimum corporate tax" (if it wasn't for WTO rules, countries cou

The vast majority of countries are WTO members. Arguably the WTO is both the rationale for a "minimum corporate tax" (if it wasn't for WTO rules, countries could introduce tariffs and other trade barriers specific to certain countries to deter registration in tax havens) and the most likely way such a thing would be realised (in practice it would probably be "you can set your rate below this, but if you do WTO members are free to set higher tariffs on your produce than other countries")