The information was transmitted in advance of former IRS official Lois Lerner's meeting the same month with Justice Department officials about the possibility of using campaign-finance laws to prosecute certain nonprofit groups. E-mails between Lerner and Richard Pilger, the director of the Justice Department's election-crimes branch, obtained through a subpoena to Attorney General Eric Holder, show Lerner asking about the format in which the FBI preferred the data to be sent.

"This revelation that the IRS sent 1.1 million pages of nonprofit tax-return data — including confidential taxpayer information — to the FBI confirms suspicions that the IRS worked with the Justice Department to facilitate the potential investigation of nonprofit groups engaged in lawful political speech," Oversight Committee chairman Darrell Issa, a California Republican, and subcommittee chairman Jim Jordan wrote in a letter to IRS commissioner John Koskinen.