Apple Inc., whose CEO Tim Cook is a major Hillary Clinton supporter and donor, has been named the biggest U.S. corporate tax avoider by a group that monitors the issue.

The tech giant avoided paying $65 billion in U.S. taxes on $215 billion its offshore subsidiaries took in last year, according to a new report from Citizens for Tax Justice (CTJ), a progressive Washington D.C. think tank.

The study found that Fortune 500 companies avoided paying $716 billion in U.S. taxes on $2.4 trillion in offshore profits booked last year. Corporations’ use of so-called tax inversions has become a presidential campaign issue, with Clinton criticizing companies that set up offshore subsidiaries in order to lower their federal income tax payments.

“Congress should act immediately to prevent corporations from engaging in inversions, where businesses move their corporate residence abroad on paper in order to escape paying their fair share of taxes,” reads a post on Clinton’s campaign website laying out her corporate tax policy.

“These corporations benefit from access to the most talented workforce in the world, billions of dollars in public investment in basic research, and the robust American legal system, yet trade in their U.S. identity to avoid paying their fair share,” it continues, adding that “inversions put smaller American businesses at a disadvantage.”

[dcquiz] But Clinton has avoided mentioning Apple in her critique.

That could be because Cook is a major backer of Clinton’s campaign and her family charity, the Clinton Foundation. In August he hosted a $50,000-a-ticket fundraiser for the former secretary of state at his home in the San Francisco area. A co-host of the function was Apple executive Lisa Jackson, the former head of the Environmental Protection Agency who was embroiled in a scandal involving her use of a pseudonymous email account while in office.

Jackson also sits on the board of the Clinton Foundation. Cook, who has donated between $25,000 and $50,000 to the Clinton Foundation, has said that he met Bill Clinton through the non-profit.

Apple has avoided a hefty U.S. tax bill by utilizing three subsidiaries it set up in Ireland. According to CTJ, the tech giant pays only 4.6 percent of its offshore profits in taxes.

One of the subsidiaries is Apple Operations Inc. The iPhone maker has invested its intellectual property rights through the subsidiary, The Los Angeles Times explained earlier this year. Intellectual property constitutes 30 percent of Apple’s net profit, the company has claimed.

“A 2013 Senate investigation found that Apple has structured two Irish subsidiaries to be tax residents of neither the United States, where they are managed and controlled, nor Ireland, where they are incorporated,” CTJ notes in its report.

The report also points to a recent ruling handed down by the European Commission, which found that Apple paid only 0.005 percent of its European profits in taxes in 2014. The commission ordered the company to pay Ireland $14.5 billion it owes in back taxes.

Cook has denied allegations that Apple avoids paying U.S. taxes. He called the suggestion “total political crap” during a “60 Minutes” interview last year.

But he seemed to undercut his own claim in the interview. While saying that “Apple pays every tax dollar we owe,” he added that he didn’t think it would be “reasonable” to re-patriate profits earned overseas to the U.S. Doing so would mean that Apple would have to pay nearly 40 percent of those profits in taxes to the IRS.

In addition to fundraising for Clinton’s presidential bid, Cook has a personal relationship with Bill Clinton, he has said.

In August, Cook told The Washington Post that he sought out Bill Clinton’s advice in 2013, just before he was set to testify in front of the U.S. Senate regarding corporate tax policy.

“For the hearing [before the U.S. Senate’s Permanent Subcommittee on Investigations about Apple’s tax practices in 2013], I’ve never testified in front of Congress before. So I called up [Goldman Sachs CEO] Lloyd Blankfein, because I looked back to say who’s done this before? I knew Lloyd and thought he’d be honest with me. I called up President Clinton,” Cook told the newspaper.

“He knows a lot about the politics,” he said of Clinton. “I’d not met him through a political connection. I’d met him through the foundation.”

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