Sarah Anderson, a veteran analyst at the Institute for Policy Studies in Washington, D.C., has been the lead author of the Institute’s annual executive pay report ever since 1993.

On CEO pay, Anderson sighs, “I sometimes think I’ve seen everything.”

And then came the research for this year’s report — released last Wednesday — and the results floored even Anderson.

Last year, the Institute for Policy Studies researchers discovered, CEOs at 25 of America’s largest corporations — powerhouses that range from Boeing and Verizon to Prudential and G.E. — took home more in personal compensation than the companies they run paid Uncle Sam in federal corporate income tax.

In 2010, these 25 companies averaged a whopping $1.9 billion each in global profits. Yet they actually came out ahead last year at tax time. Uncle Sam owed them money, an average $304 million in tax refunds and credits.

The CEOs who call the shots at these 25 companies make up a quarter of 2010′s 100 highest-paid CEOs. Their average take-home last year: $16.7 million.

How could the companies these 25 CEOs rule be so profitable — and so generous to their top execs — yet end up paying Uncle Sam so precious little?

Giant corporations like these, explains IPS study co-author Chuck Collins, are essentially “rewarding CEOs for aggressive tax avoidance.”

That reality has caught the eye of Rep. Elijah Cummings, the top Democrat on the House Oversight and Government Reform Committee. Last week, at the release of the new IPS study, Cummings called for hearings to examine “why CEO pay and corporate profits are skyrocketing while worker pay stagnates.”

The new IPS report, Executive Excess 2011: The Massive CEO Rewards for Tax Dodging, puts numbers on this soaring and stagnation. Last year, the study documents, CEOs at America’s S&P top 500 corporations saw their average pay jump 27.8 percent. Average worker pay rose just 3.3 percent.

The aggressive tax dodging that’s enriching corporations and CEOs, the IPS analysts add, doesn’t actually break any laws. Corporate America has seen to that — by just as aggressively gaming the political system to stud the tax code with loophole after loophole.

In fact, 20 of the 25 major corporations that paid their CEO more than Uncle Sam last year, notes Executive Excess 2011, “also spent more on lobbying lawmakers than they paid in corporate taxes.” And 18 of the 25 “gave more to the political campaigns of their favorite candidates than they paid to the IRS in taxes.”

This corporate lobbying and campaign cash has, over the years, created a tax code that offers CEOs a wide array of tax-dodging options. Many involve tax havens. Of the 25 top firms that paid their CEOs more than Uncle Sam last year, Executive Excess points out, 18 sport tax haven subsidiaries.

The over 550 tax haven subsidiaries of these 18 firms make shifting profits offshore — and beyond the reach of federal tax collectors — almost effortless. One example of this effortlessness: the shell game known as “transfer pricing.”

To play this “transfer” game, a corporate chief typically hands a tax haven subsidiary control over the U.S.-based firm’s “intellectual property,” assets that might range from patents to logos. The shell company then charges the U.S.-based operation inflated royalties for the right to use this property.

The U.S.-based concern happily tallies these inflated royalty costs, adds them in with the company’s other regular expenses, and proceeds to tell the IRS that the company’s U.S. operations have lost money for the year. The resulting profits from all this scheming pile up, in turn, on the books of the tax haven subsidiary, where they face rock-bottom tax rates — or no taxes at all.

Last week’s IPS study drew extensive media coverage, from national dailies like the New York Times and Washington Post to top global news services. Reporters at many of these outlets asked the corporate giants the IPS study spotlights to defend themselves.

Some firms, like Bank of New York Mellon, offered no defense. Others, like Ameriprise and General Electric, argued they weren’t dodging taxes. They were merely “deferring” them.

The tax code does indeed let corporations “defer” taxes, a power the code does not grant to individual taxpayers. These deferrals, notes Executive Excess 2011 co-author Scott Klinger, amount to interest-free loans to corporations.

Even better — for corporations — the deferred taxes may go unpaid for decades. Taxes on earnings held offshore, for instance, do not come due until those earnings slide back into the United States. Adds Klinger: “If these funds are never brought home, the taxes are never paid.”

Verizon and eBay led the corporate pushback last week against the new IPS study. eBay charged that IPS had “misrepresented” the company’s tax situation. A Bloomberg reporter, in response, asked eBay and Verizon to disclose their exact 2010 federal tax return information. Both declined to make that disclosure.

Other reporters covering the corporate pushback told IPS that the corporate media relations officers that had contacted them couldn’t themselves explain what the numbers in the tax footnotes of their own corporate reports meant.

Corporations, IPS noted Friday in a reaction to the pushback, seem to complain “almost every time a story is written about a particular corporation’s tax position.” Yet these same corporations resist reforms that would require all companies to disclose clearer data on “what they actually pay in taxes.”

This year’s Institute for Policy Studies Executive Excess report offers outraged readers a guide to all the significant reform proposals — inside and outside Congress — on the tax and pay games CEOs play.

IPS has also created an action page online to help Americans push corporate tax and pay reform forward. And that reform, after this year’s Executive Excess, has seldom seemed more desperately needed.

“We have,” as the new 2011 Executive Excess sums up, “a corporate tax system today that works for top executives — and no one else.”

Sam Pizzigati edits Too Much, the online weekly on excess and inequality published by the Washington, D.C.-based Institute for Policy Studies. Read the current issue or sign up at Inequality.Org to receive Too Much in your email inbox.