General Electric wants to buy France's Alstom; Pfizer is chasing Britain's AstraZeneca -- US companies are looking hungrily at European rivals. But the reason is not just to grow. The American giants, at least in part, are looking to avoid potentially large tax bills back home. US companies have accumulated massive piles of profits offshore, but do not want to bring the money home because of the 35 percent chunk they will have to pay the government to do so. So instead of paying out the profits to shareholders, or making US investments, they are spending the money offshore. The large deals announced this week are fueled by these offshore cash piles. General Electric wants to spend possibly $14 billion to buy the French company's power generation unit, which complements its own. Pfizer has made one of the largest buyout offers ever: $100 billion for the British drugmaker AstraZeneca. "The tax was a significant factor in making them look for acquisitions outside the US," said Robert Pozen, the former chairman of MFS Investment Management. The United States is among a handful of countries that taxes companies on all their earnings, whether made inside or outside the country. And the 35 percent rate is one of the highest in the world. But the tax only hits the offshore earnings when they are repatriated. That is a key reason why US companies hold a total of $2 trillion offshore, according to Audit Analytics data. And with lower tax rates, Europe becomes an inviting destination to spend it. Ian Read, Pfizer's chief executive, himself admitted that taxation was an important issue in the AstraZeneca offer, so far rebuffed by the British company. The US tax rate is "uncompetitive," he said, adding that a combined Pfizer-AstraZeneca would have its corporate domicile -- where it is taxed -- in Britain and operating headquarters in the United States. GE, which has a $57 billion war chest offshore, would not provide any details on the reasons for its Alstom bid. But there is the potential for many more deals. Apple keeps $54 billion offshore. It has not made any big buys outside of the country, and some shareholders have been clamoring for it to divvy the money out to them. The company has recently come around to distributing some, but instead of bringing the money back and see it taxed, it is borrowing cash to pay out to investors. -- 'The worst system in the world' -- Analysts say the tax issue cannot be the only motivation behind the proposed European acquisitions. "The (tax) incentive is probably less than it might seem," said Chris William Sanchirico, co-director of the Center for Tax Law and Policy at the University of Pennsylvania Law School. The tax issue "makes a deal that would be kind of so-so under normal circumstances better," said University of Michigan professor James Hines. "But it doesn't turn a loser into a winner." Experts agree that US tax rules doubly penalize the country: it does not get any income from the profits, and it does not benefit from their being invested or distributed inside the country. "They can't use that money to buy US companies, they can't use it to build facilities in the US, they can't use this money to pay dividends to their shareholders," said Pozen. "It's a very serious problem because this money isn't helping economic growth in the US." Victor Fleischer, a tax law specialist at the University of San Diego, was more direct: "It's the worst system in the world," he said. Politicians agree that the US tax code needs reform, but disagree on how to make the changes. In late November, Democrats proposed a sweeping reform that would lower the tax rate while banning the holding of profits offshore. But Republicans have opposed all the reforms proposed by their rivals, especially ahead of what promises to be a toughly fought congressional election in November. The worry is that companies will increasingly seek to reduce their US tax bill -- and deny the US government needed funds -- by using accounting measures to push even more income abroad, said Matt Gardner, executive director of the Institute on Taxation and Economic Policy. "Our concern is that the next step is that they will even shift their US profits on paper offshore," he said.