That total included $4 million for an August 2010 conference in Anaheim, Calif., for which the agency did not negotiate lower room rates, even though that is standard government practice, according to a statement by the House Oversight and Government Reform Committee.

Instead, some of the 2,600 attendees received benefits, including staying in expensive presidential suites. In addition, 15 outside speakers were paid a total of $135,000 in fees, with one paid $17,000 to talk about “leadership through art,” the House committee said.

The report by Treasury Department’s inspector general, set to be released Tuesday, comes as the IRS already is facing bipartisan criticism after agency officials disclosed they had targeted tea party and other conservative groups seeking tax-exempt status to extra scrutiny.