The planned merger of Pfizer and Allergan, with the new corporate home to be based officially in Ireland, draws attention again to corporate inversions, including the latest issue of Bloomberg Businessweek.

The transaction is structured so that Dublin-based Allergan is technically buying its much larger partner, a move that makes it easier for the company to locate its tax address in Ireland for tax purposes, though the drugmaker’s operational headquarters will be in New York. Pfizer Chief Executive Officer Ian Read will be chairman and CEO of the new company, with Allergan CEO Brent Saunders as president and chief operating officer, overseeing sales, manufacturing and strategy. …

… [I]f the new company is able to establish itself abroad for a lower tax rate, a controversial process called an inversion, it will be the largest such move in history.

The U.S. Treasury Department has increasingly targeted such strategies, most recently announcing new guidance on how it will value assets owned by U.S. companies that undertake inversions. The U.S. has the highest tax rate for businesses in the world, at 35 percent, and is one of the only countries to tax corporate profits wherever they are earned. Previous moves by the U.S. Treasury have derailed other proposed inversions, including AbbVie Inc.’s plan to buy Ireland’s Shire Plc for an estimated $52 billion.

Read said in an interview that the merger team reviewed the new Treasury rules when they were released last week and decided to proceed with the transaction as the companies had agreed to structure it previously.

Read has already reached out to lawmakers in both houses of Congress, including Senate Majority Leader Mitch McConnell, and is calling the White House Monday, according to a person with knowledge of the matter. His pitch is that that the deal will help the companies invest in more innovative drugs and that Pfizer Plc would have 40,000 U.S. employees at the close of the transaction.

The $160 billion transaction would make Pfizer the biggest company in Ireland, which has a $200 billion economy.

Those who dislike corporate inversions could help thwart them in a way that enhances economic growth: reform or repeal the corporate income tax.