by: Catherine Dunn

How much does Apple, the world’s most valuable company, pay in taxes? About 9.8 percent–less than a third of the U.S.’s 35 percent top corporate income tax rate–according to a report being published Tuesday (aka, Tax Day). That’s down from Apple’s tax rate of 24.8 percent in 2009 and 14.7 percent in 2010.

Apple isn’t alone in the downward trend. Among a sample of 30 high-tech companies in the Fortune 500, their average effective tax rate has steadily decreased in recent years–from 23.6 in 2009, to 19.9 percent in 2010, and down to 16 percent in 2011. Meanwhile, collective profits of these companies rose, from approximately $98 billion in 2009, to $153 billion in 2010, and up to more than $181 billion in 2011.

The amount of cash held overseas collectively by those same companies–a group that also includes Microsoft and General Electric–grew 21 percent, from 2010 to 2011, reaching nearly $430 billion last year. The group also added 51 subsidiaries abroad between 2010 and 2011, including 19 subsidiaries in jurisdictions that are considered tax havens, according to the analysis.

The report, “Tech Untaxed,”