The Irish government and Apple Computer will appeal the European Commission's ruling that the tech giant pay as much as 13 Billion Euros (AU$18.65 Billion) in back taxes that Dublin doesn't want.

After a three-year investigation, the Commission in August ruled that massive tax breaks amounted to an illegal subsidy.  Apple was paying less than one percent, a rate startlingly lower than the standard rate of Irish corporate tax, which is 12.5 percent.

But Ireland claims that the EU misread the deal and doesn't understand Irish tax law:  "Ireland did not give favorable tax treatment to Apple - the full amount of tax was paid in this case and no state aid was provided," finance ministry said in a strongly-worded statement.  "Ireland does not do deals with taxpayers."

But while Ireland maintains the EU went after its arrangement with Apple because the maker of the iPhone is "convenient target because it generates lots of headlines", the Commission has targeted other deals in other countries:  In 2015, the commission told the Netherlands to recover as much as 30 Million Euros from Starbucks, while Luxembourg was ordered to recover a similar amount from Fiat.

The amount of the back tax bill, 13 Billion Euros, is about 66 percent of Ireland's social welfare costs, or all of its healthcare budget.  But for Apple, it is only 27 percent of last year's profits.  For that reason, many in the opposition believe that Dublin shouldn't reject this windfall.