The Internal Revenue Service wrongly targeted conservative groups for additional scrutiny of their tax-exempt status, confirming what many tea party-linked organizations have alleged for over a year.

Lois Lerner, director of the Exempt Organizations Division, apologized for the practice at a conference in Washington, saying that it originated among low-level workers in Cincinnati. 

Conservative groups have been arguing for over a year that they have been inappropriately targeted by the IRS. In February of 2012, 16 tea party-related organizations claimed that they were being harassed by the agency after receiving detailed questionnaires asking about their political views and activities. Twelve Republican senators sent a letter to IRS Commissioner Douglas H. Shulman calling on the tax agency to conducts its inquiries in an “even-handed and transparent manner.” Shulman told Congress that there was no targeting of anyone.

In a statement, the IRS said that career employees in Cincinnati were attempting to deal with a huge increase in the number of applications for section 501(c)(4) status double. "While centralizing cases for consistency made sense, the way we initially centralized them did not," the statement says. "Mistakes were made initially, but they were in no way due to any political or partisan rationale. We fixed the situation last year and have made significant progress in moving the centralized cases through our system."

All applications "received the same, even-handed treatment, and the majority of cases centralized were not based on a specific name," the statement adds.

According to the IRS, "new procedures were In addition, new procedures also were implemented last year to ensure that these mistakes won’t be made in the future."

“We knew from the very start that this intimidation tactic was coordinated and focused directly on specific organizations,” said Jay Sekulow of the American Center for Law and Justice, who is representing the tea party groups. “It took the threat of legal action to get the IRS to make this admission. And while many of the organizations we represent have finally been granted tax-exempt status, we demand the IRS to immediately approve the pending applications for the remainder of our clients.”

Tax-exempt social welfare nonprofit groups are allowed to engage in political activity with minimal disclosure, but only if the primary purpose of the group is deemed non-political. Watchdogs have asked the IRS to investigate such groups on both sides of the political spectrum, such as Crossroads GPS and Priorities USA.