IRS Commissioner John Koskinen testifies Friday on Capitol Hill. Koskinen was asked to explain the disappearance of emails that could relate to a probe into the targeting of Tea Party groups. J. Scott Applewhite/AP hide caption

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Former Internal Revenue Service official Lois Lerner speaks March 5 on Capitol Hill during the House Oversight and Government Reform Committee hearing on the the agency's targeting of Tea Party groups. Lauren Victoria Burke/AP hide caption

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Former IRS official Lois Lerner, during March 5 testimony before the House Oversight and Government Reform Committee. Lerner has repeatedly invoked the Fifth Amendment during congressional appearances on the scandal. Lauren Victoria Burke/AP hide caption

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House Ways and Means Committee Chairman Rep. Dave Camp, R-Mich. (center), flanked by the committee's ranking member, Sander Levin, D-Mich. (right), and Sam Johnson, R-Texas, listen on Capitol Hill April 9 as the panel debates whether IRS official Lois Lerner's refusal to testify to Congress deserves criminal prosecution. J. Scott Applewhite/AP hide caption

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Conservatives have criticized the new Internal Revenue Service rules for political dark money as an Obama administration attempt to gain political advantage. Susan Walsh/AP hide caption

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Lois Lerner, the head of the IRS division that handles applications for tax-exempt status, listens to opening statements during a hearing before the House Oversight and Government Reform Committee before refusing to testify on May 22. Chip Somodevilla/Getty Images hide caption

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Ty Warner, creator of Beanie Babies toys, attends the 2003 American International Toy Fair in a rare appearance to celebrate the 10th anniversary of the Beanie Babies toy line. Chris Hondros/Getty Images hide caption

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A waiter serves patrons at Tony's Restaurant, part of the Casablanca Hotel in New York's Times Square. The custom at some restaurants of automatic gratuities for larger parties might change because of an IRS rule change. Don Emmert/AFP/Getty Images hide caption

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