In the US, executive orders cannot change tax law, since the "power of the purse" is constitutionally reserved for congress. If you're thinking of the Iran nuc

In the US, executive orders cannot change tax law, since the "power of the purse" is constitutionally reserved for congress. If you're thinking of the Iran nuclear deal, that's head-of-state stuff where the president is considered to have more powers (though of course it still was never a treaty, so could be/was scrapped easily by the next administration).