Apple's Irish tax bill could top $20 billion if it does not succeed in overturning an European Commission ruling, one expert warned on Wednesday.
On Tuesday, the European Commission, which is the legislative arm of the European Union, ruled that Ireland must recover up to 13 billion euros ($14.5 billion), as well as a sizable interest, in "illegal tax benefits" from the tech giant.
Due to an unusual global tax structure, the iPhone maker's effective tax rate in Ireland was a mere 0.005 percent in 2014.
Independent economist Seamus Coffey told CNBC's "Squawk Box" that the final payment once interest penalties are taken into account, if ever paid, could amount to as much as 10 percent of Ireland's national income. "The European Commission wanted to make a splash," he said.
But Apple's operations in Ireland, where about 6,000 people are employed, do little to contribute to the bulk of the company's profits outside the Americas.
"In Ireland, you don't have substantial Apple profits being generated," said Coffey. "They handle the logistics, administration and the back office stuff. The research and development, manufacturing and key management decisions aren't taking place [in the country]."