Although President Obama hasn’t referred to it as such, several times recently he has called for global taxation of the profits of multi-national corporations.
In the absence of a unitary tax on a multinational corporation’s worldwide income, it is a simple matter to manipulate the financial transactions of a company to keep from paying taxes to a state or to the federal government. Here’s how it works:
Corporation A in say, Japan, owns Corporation B in Japan and Corporation C in California. Corporation B makes car components and Corporation C assembles them in California. Corporation B gouges Corporation C in invoicing the company for the car components, so that on the books in California, very little profit is made. However, Corporations A and B make out like bandits. Even though their profits were generated in California, they pay next to nothing in California taxes.
A unitary tax would tax Corporation A because it owns Corporation C, so it can’t escape taxation by making it look like the profit was made overseas.