Federal employees owe over $1 billion in unpaid federal income taxes, according to this report. Over $10 million of that is owed by Congressional staffers. From the Washington Post story:
on Capitol Hill, 684 employees, or almost 4 percent, of the 18,000 congressional staffers owed taxes in 2010 – a jump of 46 workers from 2009. Four percent of House staffers owed $8.5 million and 3 percent of Senate employees owed $2.1 million, the IRS said.