Précis: Mr. and Mrs. Wynne were residents of Maryland. They had sources of income in a number of states and sought tax credits in Maryland for income taxes paid to those other states. They were granted tax credits against Maryland “state” taxes but not Maryland “county” taxes (“county” taxes being in fact imposed and collected by the State of Maryland).
Comptroller v. Wynne - SCOTUS: Double taxation of out-of-state income by Maryland violates Commerce ClausePlus >