"You're getting paid for being here today, right?" Reed asked, to which Miller, his smile gone, dryly replied: "Right."
After the hearing, Camp described a "disturbing lack of detail and information" during testimony.
"We're going to continue to pursue this, as a committee, to find out who knew what, when, where, and how these decisions were made and how they were carried out," he said.
Earlier he told reporters the panel wanted unspecified records from Miller's tenure at the IRS.
Democrats sought to balance rejection of any perception of political manipulation by the IRS in the case with an effort to portray the situation as a poorly managed increase in demand for tax exempt status by political groups.
Rep. Jim McDermott, D-Washington, said the vast majority of the increased applications for tax exempt status after the Citizens United decision were from "far right groups," while fellow Democratic Rep. Richard Neal of Washington said the conservative organizations wanted to be involved politically without revealing donors -- as allowed for the 501 (c) (4) groups under the federal tax code.
"It all started right after Citizens United," McDermott said, adding that political groups "saw the door open" and thought that "we can get in, we can do political advertising."
He described a difference between "stupid mistakes and deliberate mistakes," adding that the IRS officials handling the requests took a shortcut "they deeply regret."
Democrats repeatedly asked George, who wrote the report on the controversy, to reiterate that there was no evidence of political motivation. Each time, George agreed his review found no such evidence.
Rep. Sander Levin, the panel's ranking Democrat, specifically cited the former IRS commissioner, Douglas Shulman, for what he called misleading Congress on the issue. Shulman was not a witness at Friday's hearing, but is scheduled to appear at other congressional hearings next week.
According to the report by George, the agency developed and followed a faulty policy to determine whether the applicants were engaged in political activities, which would disqualify the groups from receiving tax-exempt status.
The controversial move began in early 2010 and continued for more than 18 months, the report said, declaring that "the IRS used inappropriate criteria that identified for review Tea Party and other organizations applying for tax-exempt status based upon their names or policy positions instead of indications of potential political campaign intervention."
Among the criteria used by IRS officials to flag applications was a "Be On the Look Out" list, which was discontinued in 2012, the report said.
The criteria included:
-- Whether "Tea Party," "Patriots" or "9/12 Project" was referenced in the case file.
-- Whether the issues outlined in the application included government spending, government debt or taxes.
-- Whether there was advocating or lobbying to "make America a better place to live."
-- Whether a statement in the case file criticized how the country is being run.
-- Whether it advocated education about the Constitution and the Bill of Rights.
Conservative groups complain their requests were delayed for months or even years through the targeting that sought to prevent ineligible political groups from getting tax exempt status. Miller testified Friday that determining the political nature of groups was one of the hardest tasks of IRS officers tasked with assessing requests for tax exempt status.
IRS officials, according to the report, did not consult anyone beyond the agency about the development of the additional screening criteria. They believed that the criteria they came up with were a screening shortcut meant to help with the influx of applications, the report said.
The IRS scrutiny began after the Citizens United case. Following the ruling, the number of politically oriented groups seeking tax exempt status as social welfare organizations under section 501 (c) (4) of the federal tax code increased greatly at a time when the federal government, including the IRS, was dealing with austerity measures that reduced or stagnated personnel and resources.
Some Democrats pointed to budget cuts at the IRS as a reason for the agency's inability to properly enact an increasingly complex tax code.
However, the IRS watchdog found that the criteria used to flag potential political applications resulted in substantial delays and the request of unnecessary information from the groups.
The investigation by the Treasury inspector general for tax administration was initiated after congressional complaints began to surface in the media in 2012 that the IRS was targeting conservative groups and holding up applications.