The Treasury Inspector General issued a report today finding the IRS used "inappropriate criteria" to target conservative groups. Long story very short: In response to a surge in 501(c)(4) applications, some IRS officials took short-cuts to determine if the organizations were acting in an overtly political manner, which would violate their tax-free status. The IRS told the group to use fairer and less politically charged criteria. And they didn't.
Here is the president's response to today's report (via Ryan Lizza)
Here is the summary of the Inspector General report:
And here is the report in full: