What kicked off the Internal Revenue Service’s targeting of Tea Party groups? The Treasury Department’s Inspector General apparently knows but the rest of us cannot. His report on the scandal includes three timelines of events, but in each case, the first item in the timeline has been redacted.

On top of page 13 is a graph titled “Figure 5: Timeline of Events and Delays Involving the Processing of Potential Political Cases (******1***** through May 2012)”  that redacts the first item, not even giving a date. A spokesman for the House Oversight and Government Reform Committee confirmed the “****1****” item was Treasury’s style for redactions.

The mystery date was apparently February 25, 2010, based on two appendixes in the back of the report.

On page 30, there is an appendix titled “Timeline of Written Criteria for Identifying Potential Political Cases.” The following page has another appendix titled “Comprehensive Timeline of Events.” These are appendixes six and seven of the report. On each page, the first item on the respective timelines has also been redacted.

Appendix 6 on page 30 states “The following illustrates the changes to the written criteria provided to Determinations Unit employees for identifying applications for the team of specialists. ” The first item on the timeline is “February 2010.” Two sentences appear to have been redacted.

Appendix 7 on page 31 states: “The following chart illustrates a timeline of events from February 2010 through July 2012 involving the identification and processing of potential political cases.” The first item on the timeline is “February 25, 2010.” The rest has, again, been redacted.

The rest of the report references dates earlier than February, 2010, in laying out how the IRS came to target Tea Party groups. But the reference to February in both appendixes indicates something particularly noteworthy happened then in the evolution of the IRS’s policy. What was it?

A spokesman for the IRS referred any inquiries to the Treasury Department. A spokeswoman a Treasury referred the Examiner‘s question on the matter to its Inspector General. The IG’s office has not responded to a request for comment. (UPDATE: IG spokesman David Barnes emails: “As noted on the cover page of the report, some items have been redacted because the information could identify a specific taxpayer.”)

Thanks to alert reader Jared M. of Houston, Texas, for pointing this out.