By Patrick McCormick (October 16, 2018, 4:20 PM EDT) -- As most practitioners are aware, United States nonresident aliens — that is, individuals who are neither citizens nor residents of the United States — are subject to a far narrower tax scope (both for income and transfer tax purposes) than their United States citizen/resident counterparts (with U.S. citizens and residents referenced as "U.S. taxpayers," herein). Typically, nonresident aliens are taxable by the United States only on income sourced to the country (or, for transfer tax purposes, assets sitused in the United States). In a growingly global world, individuals switch between nonresident alien and U.S. taxpayer classifications with increasing regularity (by, for example, becoming a United States green card holder). Cognizance of the tax ramifications of such a switch is paramount. This article provides an overview of tax rules applicable to nonresident aliens, then delves into common considerations relevant — and opportunities available — prior to becoming a United States taxpayer....