The Senate Finance Committee has scheduled a hearing for Tuesday on international competitiveness and the rush by U.S. corporations to move their headquarters abroad through “inversions” that reduce their taxes. The inversions are legal under U.S. tax law, but they have drawn sharp criticism because they reduce federal tax revenue and, some argue, represent a withdrawal of support for the country that provided the environment that enabled them to succeed.

Fridley-based Medtronic, among these companies, is planning to move its headquarters to Ireland in an inversion. Medtronic argues that its acquisition of Dublin-based Covidien is motivated largely by the strategic fit of the two companies and not by tax advantages.

Topics ranging from how the tax code can be improved so U.S. companies can become more globally competitive to concerns about erosion of the tax base, profit shifting and inversions are expected to be discussed at the hearing.

Among the witnesses slated to testify is Robert Stack, deputy assistant secretary for international tax affairs for the U.S. Department of the Treasury. Last week, U.S. Treasury Secretary Jacob Lew sent letters to leading members of the Senate Finance Committee and the House Ways and Means Committee, urging them to take prompt action to stop the rush of U.S. companies to move their headquarters out of the U.S.

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Also scheduled to testify is Allan Sloan, senior editor at large for Fortune magazine. Sloan wrote a cover story, for the current issue of the magazine, critical of the companies moving their headquarters out of the U.S. to gain tax advantages.

When Medtronic’s $43 billion deal was announced in mid-June, it was the largest such inversion thus far. But on Friday, Illinois-based AbbVie, recently spun off from one of the Chicago area’s largest multinationals, Abbott Laboratories, topped the Medtronic inversion by announcing a $54 billion transaction to buy Shire, a leading European competitor. The combined company will be based on Jersey, an island in the English Channel.

AbbVie predicted a corporate tax rate of 13 percent for the combined companies by 2016 vs. 22.6 per cent last year for AbbVie alone. Medtronic has not disclosed details on how much its tax rate, or the taxes it actually pays, could fall as a result of its acquisition of Covidien.

Sen. Ron Wyden, the Oregon Democrat who chairs the Senate Finance Committee, has a suggested a ban on inversions.

But a flat-out ban could face significant opposition in Congress. If any proposal could somehow break through the persistent gridlock in Congress, it would more likely be a temporary curb designed to stem the rush of inversions for now. Such a plan, a two-year curb on inversions, has been proposed by Sen. Carl Levin, D-Michigan. House Republicans want any changes to be made as part of a broad overhaul of corporate taxation. Another issue is whether curbs would be retroactive — thus upending deals already concluded, like the Medtronic transaction.

The U.S. has the highest statutory federal corporate tax rate in the world, 35 percent, though many companies pay a much lower rate by taking advantage of various provisions. Many critics of the current U.S. tax laws have been calling for an overhaul of corporate taxation, but Congress has been unable to agree on changes.

Last week, The New York Times and other media outlets reported that efforts to limit or block inversions will have difficulty gaining traction in the Republican-controlled House of Representatives.

Other witnesses scheduled to testify Tuesday:

Pascal Saint-Adams, director of the Centre for Tax Policy and Administration at the Organization for Economic Co-operation and Development in Paris.

Mihir Desai, Mizuho Financial Group Professor of Finance at the Harvard Business School and a law professor at the Harvard Law School.

Peter Merrill, director of the National Economics and Statistics Group at PricewaterhouseCoopers in Washington, D.C.

Leslie Robinson, associate professor of business administration at Dartmouth College’s Tuck School of Business.

The hearing, which starts at 9 am CDT, is titled “The U.S. Tax Code: Love It, Leave It or Reform It.”