The percentage of corporate tax returns audited by U.S. collectors fell about 9 percent in 2008 and was down nearly 20 percent from about a decade earlier, an inspector general report released on Monday said.

About 15.3 percent of returns filed by corporations with $10 million or more in assets were examined by the Internal Revenue Service last fiscal year, down from about 16.8 percent in 2007, the Inspector General for Tax Administration for the U.S. Treasury Department said in its annual report.

In 1999, about 19 percent of tax returns for the group were examined by tax collectors. The rate of examination ranged between 15 and 19 percent in the intervening years, with the exception of a 20 percent rate in 2005.

The IRS's enforcement staff has been whittled down in recent years, a response to fervent complaints by some U.S. lawmakers critical of what was characterized as aggressive tax collection.

After several years of improved results, many collection function activities and results declined during FY 2008, the report said.

The enforcement staff shrank 20 percent to 14,900 at the end of 2008, down from 18,700 in 1999, the report said.

President Barack Obama has proposed doubling the agency's enforcement budget for 2010, including hiring about 800 new staffers just to enforce international tax law. That is part of a wider effort by the administration to crack down on what it calls the abusive use of tax loopholes and outright tax evasion.

Enforcement revenue fell in 2008, though that interrupted a steady rise in the past decade or so, the report said.

The IRS collected $2.75 trillion in fiscal year 2008, a record.

The report did not make any specific recommendations, but noted the enforcement of tax laws is among the key high-risk areas consistently cited by the Government Accountability Office.

The tax gap -- the difference between what is owed and what is collected -- was about $345 billion in 2001, the last year it was examined, according to the government.

To see the full report: http://www.ustreas.gov/tigta/auditreports/2009reports/200930082fr.pdf

(Editing by Gerald E. McCormick)

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