Attention, millionaires, the watchful eye of the Internal Revenue Service is trained on you. During last year's tax season, 30 percent of multimillionaires were audited, the agency said. Overall, just 1.1 percent of individual income tax returns were checked.

Attention, millionaires, the watchful eye of the Internal Revenue Service is trained on you. During last year's tax season, 30 percent of multimillionaires were audited, the agency said. Overall, just 1.1 percent of individual income tax returns were checked.

Taxpayers making an adjusted gross annual income of $10 million or more are increasingly on the IRS' radar — in 2010, just 18 percent of them faced audits, according to a report from the agency. Nearly 21 percent of Americans making between $5 million and $10 million had their returns inspected, the IRS said; 12 percent of millionaires making less underwent the same process.

From Oct. 1, 2010, through Sept. 30, 2011, the agency said it collected $2.4 trillion in taxes from 234 million processed returns, up from the $2.3 trillion collected the year before. It was the first year of increased revenue since 2008.

The IRS said more than 133 million tax returns — including more than three-quarters of all individual returns — were filed online. More than eight in 10 individual returns resulted in refunds — a total payout of $338 billion (among all tax returns, nearly $415.9 billion was refunded).

Nearly 4,700 criminal investigations were completed last year, the agency said, with 1,802 resulting in incarcerations.