For many tax advisers outside the U.S., state corporate income tax is viewed simply as an add-on to the Federal tax.  This relatively simplistic view ignores the requirements of U.S. Federal and Constitutional law that an activity must have a connection – called a nexus – to a state before tax can be imposed on profits allocated to the state.  Alvan L. Bobrow of Akerman LLP in New York explains the concept of “economic nexus,” a way by which digital activity within a state may trigger exposure to state tax.  Companies that license marketing intangibles should be particularly wary.