Apple Inc. was ordered to pay as much as 13 billion euros ($14.5 billion) plus interest after the European Commission said Ireland illegally slashed the iPhone maker’s tax bill, in a record crackdown on fiscal loopholes that also risks inflaming tensions with the U.S.

The world’s richest company benefited from selective tax treatment that gave it an unfair advantage over other businesses, the European Union regulator said Tuesday. It’s the largest tax penalty in a three-year campaign against corporate tax avoidance. Apple and Ireland both vowed to fight the decision in the EU courts.

Ireland allowed Apple to pay an effective corporate tax rate of 1 percent on its European profits in 2003 down to 0.005 percent in 2014, according to EU Competition Commissioner Margrethe Vestager.

“If my effective tax rate would be 0.05 percent falling to 0.005 percent -- I would have felt that maybe I should have a second look at my tax bill,” she told reporters.

The U.S. Treasury Department, which has pushed back hard against the EU state-aid probes, said the commission’s actions “could threaten to undermine foreign investment, the business climate in Europe, and the important spirit of economic partnership between the U.S. and the EU.”

White House Press Secretary Josh Earnest said that Apple executives have shared concerns about the company’s tax treatment overseas with officials in President Barack Obama’s administration.

Administration officials are broadly concerned that what Earnest called the EU’s “unilateral approach” doesn’t undermine coordinated efforts to prevent an “erosion of the tax base.” Also, he said, they want to ensure that any actions are fair to U.S. taxpayers and U.S. businesses.

Apple, which employs about 6,000 people in Ireland, was one of the first companies caught up in the EU’s backlash against corporate tax-avoidance. The EU, like other global regulators, has targeted firms that sidestep taxes by moving around profits and costs to wherever they are taxed most advantageously -- exploiting loopholes or special deals granted by friendly governments.

David Fuller's view

Subscriber’s views on this individual case may vary but it certainly marks a deterioration in EU’s relationship with the USA – see this article from The Wall Street Journal: The EU’s Tax Attack on U.S. Business, published four days ago before the Apple case was raised.

See also Tim Cook’s message to the Apple Community in Europe.

Speaking personally, I think the democratic nation of Ireland should be free to set its own tax policies, in the interests of its own citizens.  However, Ireland is no longer a sovereign state within the EU.  The power now resides in Brussels.