time line of events

2010

March-April: IRS agents begin giving extra attention to tax-exempt applications from groups associated with the Tea Party or with a political sounding agenda in their names, such as "Patriots," "Take Back the Country" or "We the People," according to the IRS inspector general.

2011

June: Lawmakers send the first of at least eight letters asking the IRS to address complaints that conservative groups are being subjected to burdensome screening in their applications for tax-exempt status.

June 29: Lois Lerner, in charge of overseeing tax-exempt organizations at the IRS, learns at a meeting that groups are being targeted, according to the inspector general.

Dec. 16: Lerner does not divulge the information when she and others from the IRS meet staff members of the House Ways and Means Committee, according to the staff's timeline of events.

2012

January: The criteria for screening, altered after Lerner's staff meeting six months earlier, is modified again. Now the IRS is looking for references to the Constitution or Bill of Rights in the materials of organizations seeking tax-exempt status, for "political action type organizations involved in limiting/expanding government," and more.

March 22: IRS Commissioner Douglas Shulman tells Congress there is "absolutely no targeting" of groups based on political views.

May: Lerner does not divulge the flagging in letters to two lawmakers inquiring about it.

May 3: Deputy Commissioner Steven Miller is told by staff that applications for tax-exempt status by Tea Party groups were inappropriately singled out for scrutiny, the IRS said.

June 15: Miller responds to a letter from Rep. Charles Boustany, R-La., and does not concede that conservatives had been singled out.

July 25: Miller testifies to a House subcommittee but does not divulge what he was told in May about the Tea Party screening.

Sept. 11: Miller writes a letter responding to Sen. Orrin Hatch, R-Utah, but again does not own up to the scrutiny conservatives were placed under.

Nov. 6: Elections

Nov. 15: Lerner meet with Ways and Means staff but does not acknowledge the targeting.

2013

Week of April 22: White House counsel learns that the inspector general is finishing a report about the IRS office in Cincinnati, White House spokesman Jay Carney said.

May 10: Lerner apologizes; White House counsel is said to receive inspector general's report; President Obama is said to have heard of the matter for first time.

Associated Press