In a statement announcing Lois Lerner's retirement, the IRS said federal privacy rules preclude it from commenting further, The Wall Street Journal reported.
Lerner, who headed the IR'S tax-exempt-organizations division, had been on administrative leave since shortly after the controversy erupted in May over the agency's targeting of Tea Party organizations for in-depth reviews when determining tax-exempt status.
The Journal said Lerner's attorney had not responded to requests for comment.
A Democratic congressional aide told the Journal Lerner's retirement follows an IRS review board's decision to propose her removal from the agency. The board had found she neglected her duties as director of the IRS exempt-organizations division and that she had mismanaged the office. The congressional aide told the newspaper the board found no evidence of political bias or willful misconduct.
The IRS scrutiny of dozens of Tea Party and other conservative groups began in early 2010. Democrats have said some liberal-leaning groups also came under extra scrutiny, showing no political bias exists.