General Electric, the nation's largest corporation, had a very good year in 2010. The company reported worldwide profits of $14.2 billion, and said $5.1 billion of the total came from its operations in the United States. Its American tax bill? None. In fact, G.E. claimed a tax benefit of $3.2 billion. That may be hard to fathom for the millions of American business owners and households now preparing their own returns, but low taxes are nothing new for G.E. The company has been cutting the percentage of its American profits paid to the Internal Revenue Service for years, resulting in a far lower rate than at most multinational companies. Its extraordinary success is based on an aggressive strategy that mixes fierce lobbying for tax breaks and innovative accounting that enables it to concentrate its profits offshore. G.E.'s giant tax department, led by a bow-tied former Treasury official named John Samuels, is often referred to as the world's best tax law firm. Indeed, the company's slogan Imagination at Work" fits this department well. The team includes former officials not just from the Treasury, but also from the I.R.S. and virtually all the tax-writing committees in Congress. While General Electric is one of the most skilled at reducing its tax burden, many other companies have become better at this as well.