IRS Link to Publication — Found Here

Publication 54 is a guide for those earning income in a foreign country.

There are several tax deductions which might be available and several forms and filing practices that one will need to be familiar with when taking employment elsewhere. US Citizens and long term resident green card holders will need to let the IRS know how much they are making even if they are employed in a foreign country.

Form 2555 is the one used to compute and file Foreign Earned Income. Certain trade agreements and tax treaties might influence how the employee is taxed. Form 673 helps to compute the exemption on foreign income that a worker might be entitled to.

There are deductions and exclusions available for housing costs and just for working abroad since another government might already have taxed the income. It might also be useful for a resident alien to refer to Publication 519, Tax Guide for Aliens.

Resident aliens, which are usually Green Card holders, are taxed under the same regime as US citizens, while nonresident aliens have their own set of guidelines.