You must file taxes regardless. There are treaties which will let you minimize double-taxing, so you can deduct part of taxes paid to another country. Similar to what they habe between states (which are not always great savings). Otherwise there isn't much of a difference in the Federal tax requirement, (although this law is often disregarded, except when it comes to claiming child credits ;-), it is not very easy to enforce as the host country often will not cooperate with the IRS, although as of late some Israeli banks are reportedly increasing cooperation).