As international tax nerds, we focus on cross-border transactions. That could mean individuals moving to a different country; a company exporting for the first time or doing business in a different jurisdiction; or a multitude of other items. As multi-jurisdiction experts, from time to time we get called into domestic cross-border situations. While we know domestic cross-border sounds odd, it happens daily in the context of US state taxation when advisors must determine which state has the right to tax which income. While we are not state tax experts, our cross-border work sometimes draws us to state tax issues. As an example, we were privileged to play a role in an Amicus Curiae brief recently submitted to the US Supreme Court focusing on whether a New York tax on intangible income is constitutional. The brief was submitted by the American Academy of Attorney – Certified Public Accountants, Inc. (AAA-CPA) supporting Petitioners in SAMUEL EDELMAN AND LOUISE EDELMAN v. NEW YORK STATE DEPARTMENT OF TAXATION AND FINANCE, ET AL. Special thanks to Counsel of Record, Michele B. Friend of Clark & TREVITHICK APC in Los Angeles.