One in eight people earning at least $1 million annually was audited by the Internal Revenue Service last year, making them far likelier to be examined than those making below $200,000, according to IRS data released Thursday.
Just 1 in 100 individuals earning less than $200,000 had their income tax returns examined, the IRS said.
The 12 percent of millionaire earners audited in 2011 was appreciably higher than the 8 percent who were audited in 2010. IRS officials said the high ratio was part of an effort to demonstrate that tax laws are applied fairly.
"That has been something we've concentrated on to assure that there's equity in the system, to assure that those at the lower end of the spectrum know that those at the higher end of the spectrum are subject to the same rules and enforcement as everyone else," Steven Miller, deputy IRS commissioner for services and enforcement, said in an interview.
In recent weeks, President Barack Obama and congressional Democrats have sought to boost taxes on the wealthy as a way to pay for jobs programs, a theme they are expected to continue in this presidential and congressional election year. IRS spokeswoman Michelle Eldridge said the growing portion of millionaire earners' returns audited is not related to politics.
"The IRS is an agency of civil servants, and we base our audit decisions on tax issues _ nothing else. We don't play politics here," she said.
Between 2004 and 2009, the percentage of millionaire earners audited ranged between 5 percent and 7 percent.
The data was divided into only three categories of income: below $200,000, $200,000 and up, and $1 million and higher.
About 1 in 25 people earning $200,000 and more was audited in 2011.
The IRS also audited a greater proportion of large corporations than smaller ones, the data shows.
Last year, 1 percent of corporations with assets under $10 million were audited. Among corporations with assets of $250 million and up, 28 percent were audited.
The IRS said its enforcement efforts to collect all taxes owed _ which include audits, court cases and other activities _ netted $55 billion last year. That is nearly $3 billion less than the previous year, which Miller attributed to a falloff in estate taxes and corporations writing off their losses.
All together, the IRS audited nearly 1.6 million of the 141 million individual income tax returns that were filed. In 2010 _ the most recent year available _ more than 8 in 10 individuals audited ended up paying additional taxes.
The agency collected a total of $2.3 trillion in revenue last year from individuals and businesses, including the $55 billion from its enforcement efforts.
The IRS figures also showed that:
_In 2011, the agency garnisheed wages or seized money from bank accounts 3.7 million times, put liens on property 1 million times and seized 776 pieces of property.
_77 percent of individual returns were filed electronically last year, up from 69 percent in 2010.
_70 percent of callers to IRS taxpayer information telephone lines got through, slightly less than the 74 percent who reached someone in 2010. Miller attributed that to budget cuts to the agency.
_The information IRS officials dispensed over the phone to taxpayers was accurate 93 percent of the time, the same as the previous year.
_The IRS website, http://www.irs.gov, was visited 319 million times in 2011, a slight increase.
The data was presented by federal fiscal years, which begin on the previous Oct. 1.