The latest in a string of U.S. companies buying foreign firms so they can skirt the IRS marries a burger-and-fries icon (Burger King) with coffee-and-donut icon (Tim Hortons). When the new firm reconstitutes itself in Ontario, U.S. corporate tax revenues will go on diet. Normally, these so-called inversions that cut corporate taxes can trigger a painful hike in individual income tax for shareholders.