The Twitter IPO set for Thursday has Congress all wound up — this time, about tax policy.

On Tuesday, the House Ethics Committee took the Twitter initial public offering as an opportunity to remind members they can’t participate in IPOs in a manner “other than is available to members of the public generally.”

On Wednesday, it was the Senate’s turn.

Sens. Carl Levin, D-Mich., and John McCain, R-Ariz., the chairman and ranking member of the Senate Homeland Security and Governmental Affairs Subcommittee on Investigations, reminded the public of one of a number of “inequitable special-interest tax loopholes.”

“When Twitter goes public later this week, the company may avail itself of this existing tax loophole,” a joint press release from Levin and McCain said. “Under this loophole, the company will be able to take an estimated $154 million tax deduction for a stock option compensation expense which its own books show cost Twitter only $7 million.”

The release said the loophole allows a company to report stock option compensation expenses one way on its financial statements, and report it a different way to the IRS for tax purposes.

“Nowhere else in the tax code can compensation costs produce a tax deduction several times larger than that same expense shown on its corporate books,” the release said.

Levin and McCain said the deduction is 20 times larger than the actual business expense, and the loophole is not unique to Twitter. According to Levin and McCain, data from the IRS provided to the subcommittee shows that the corporate stock option tax deductions “far exceeded” the expenses shown on corporate books — “tens of billions of dollars greater than the expenses shown on their financial statements” between 2004 and 2010.

In 2010 alone, the tax deductions amounted to nearly $20 billion, and the Joint Committee on Taxation has estimated that ending the tax policy would raise $23 billion in revenue yearly, according to the release.

And that has Levin and McCain seeing potential dollar signs.

“Given the deficit and damaging sequester cuts facing this country, this corporate stock option tax deduction is the kind of tax loophole that ought to be closed,” Levin and McCain said.