Federal prosecutors filed 1,250 tax cases in 2010, a 25.3 percent rise over 2001, USA Today reports. IRS recommendations for prosecution hit 1,507, up from 1,002 in 2001.
"The time that we're spending on tax investigations has gone up," said Steven Miller, the IRS deputy commissioner for enforcement. "That's resulted in a lot more prosecutions in that area."
The IRS also has opened at least 10 overseas investigation offices in the past two years, Miller said.
Last year's figures include charges or guilty pleas involving Americans accused of evading taxes on profits hidden in secret Swiss accounts.
Swiss bank UBS agreed last year to give U.S. authorities records for 4,450 American clients, challenging Switzerland's traditional secrecy.
And last week, a New York woman pleaded guilty to filing a false 2008 return that concealed $8.3 million in HSBC India accounts.
"We are focusing more and more on offshore; there is no question about that," Miller said.
The IRS also is cracking down on fraud by tax preparers.
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