Why does the Canadian federal government collect 1.9 percent of GDP in revenues with a 15 percent corporate tax rate, while the U.S. federal government only collects about the same (2.0 percent) with a 35 percent corporate tax rate?

One reason is that a low corporate tax rate induces higher real investment and economic growth, which in turn generates higher government revenues.

Another reason is profit shifting by multinational corporations. Over time, paper profits are steadily shifted out of countries (such as the United States) that have unfavorable tax rates and tax rules. The (now abandoned) plan for American Pfizer to merge into British AstraZeneca to save $1 billion a year on taxes was one illustration of how tax based migration works.

This May 5 story in Tax Notes International (subscription required) provides another illustration from the pharmaceutical industry:

The combined entity resulting from the proposed acquisition of U.S.-based Allergan Inc. by Valeant Pharmaceuticals would have an effective tax rate in the single digits, around 20 percentage points lower than Allergan’s current rate, according to Valeant CEO J. Michael Pearson.

Quebec-based serial acquirer Valeant on April 22 announced an offer of close to $46 billion in cash and stock in its bid for competitor Allergan, the company behind Botox. The acquisition would make Valeant the second largest company in eye health globally, ahead of Johnson & Johnson and behind Alcon.

Valeant has partnered with Allergan’s largest shareholder, Pershing Square Capital Management, led by CEO William Ackman, to solicit support for the deal from Allergan shareholders.

Ackman said he has spent time familiarizing himself with the sustainability of Valeant’s tax structure. “The company has the benefit of being based in Canada; there are some unique attributes of the Canadian tax system,” he said during an April 22 presentation to investors led by Valeant’s management team. High on the list of selling points are tax synergies that would result from the deal. The combined company would have a high single-digit cash tax rate, Pearson said, adding, “and those of you who know us know what we’re able to do there.”

Pearson may have been alluding to tax savings Valeant has achieved in the past using strategic deal structures and intellectual property migration.

Valeant, which began as a New Jersey company with an effective tax rate in the mid-30 percent range, merged with Canadian pharmaceutical company Biovail Corp. in a 2010 inversion that resulted in a combined company domiciled in Canada with offshore IP and a worldwide effective tax rate of about 5 percent. Last year Valeant bought New York-based Bausch & Lomb for around $8.7 billion cash and promptly integrated the U.S. company into Valeant’s decentralized model.

During the April 22 presentation, Valeant CFO Howard Schiller confirmed that the Allergan acquisition plan would be business as usual on the tax front: Allergan would be integrated into Valeant’s corporate structure in much the same way as Bausch & Lomb, with the new company based in Canada.

“We’ll use an installment sale approach to migrate our IP to our Irish subsidiary and, just like in Bausch & Lomb, we expect to get immediate synergies in that regard,” Schiller said, adding, “and we will have a high single-digit tax rate for the foreseeable future.”

The tax projection comes from five- to six-year models and should be welcome news to shareholders of Allergan, which expects an effective tax rate for 2014 of between 26 and 27 percent.

But Valeant is sensitive to those who might see the new effective rate as high, compared with the company’s typical low single-digit rates. “There are things that we’re looking at that we could possibly do to improve that,” Schiller said. “Over time, if we bought assets outside the U.S., which, given our footprint we’re likely to do, that would create opportunities.”