When congressional Republicans pursue discredited “scandals,” the principal complaint is about productivity: it’s a waste of time. There’s a lot of real work for Congress to do, and it’s discouraging to see lawmakers invest so much energy in pointless conspiracy theories.

But there’s a secondary complaint that gets less attention: it’s a waste of money, too.

We learned about a month ago, for example, that congressional Republicans’ inquiry into the debunked IRS controversy had cost, through mid-February, $14 million . The IRS also concluded that 255 agency employees had logged almost 100,000 hours in accommodating congressional inquiries in the matter.

And as the Associated Press reported late yesterday, it’s not the only expensive inquiry.

The Pentagon says Congress’ multiple investigations of the deadly 2012 attack on the U.S. diplomatic mission in Benghazi, Libya, have cost the department millions of dollars and thousands of hours of personnel time. In a March 11 letter, the Pentagon described repetitive requests for information from about 50 congressional hearings, briefings and interviews. The department was responding to a Feb. 4 letter from Rep. Adam Smith of Washington state, the top Democrat on the House Armed Services Committee.

“The total cost of compliance with Benghazi-related congressional requests sent to the department and other agencies is estimated to be in the millions of dollars,” the Pentagon said.

Smith wrote to Rep. Howard “Buck” McKeon (R-Calif.), chairman of the House Armed Services Committee, asking that “this witch-hunt” end.

“More than any other committee in Congress, this committee should understand the financial strain on the department of defense, which is being made worse by these ongoing and ridiculous investigations,” Smith wrote.

To be sure, when there are legitimate inquiries underway, this is money well spent, but when partisans keep baseless investigations going, long after the “scandal” has been discredited and the relevant questions have been answered, then it’s clearly little more than a waste.

It probably won’t matter. Indeed, care to guess how the House Oversight Committee is spending its morning

Darrell Issa is after a trove of Internal Revenue Service documents – and he’ll use the Oversight hearing this morning to pester the agency’s leader on why the committee hasn’t seen them. The Republican chair of the House Oversight Committee warned John Koskinen that the agency’s pace in turning over documents is testing the new commissioner’s promise to cooperate with congressional investigations. While Issa hasn’t gone after Koskinen with the same intensity he’s levied on Lois Lerner, it is possible, Issa and aides have said in the past, that if the documents don’t find their way to the Oversight panel, Congress could eye a contempt vote for the commissioner. That is far off, but today’s hearing will be pivotal in understanding just how frustrated Republicans are will the agency and how seriously Koskinen is taking Issa’s warning.