(AGI) Rome, Aug 30 - The European Commission has ordered Apple to pay Ireland 13 billion euros in unpaid taxes after its tax deal was ruled as undue "State aid". Companies based in Ireland already benefit from a maximum corporate tax rate of 12.5 percent, but the EU's competition authority found that Apple Sales International was the only company enjoying a rate on its European profits that dropped from 1 percent in 2003 to 0.005 percent in 2014. Furthermore, the company's tax structure in Ireland "did not correspond to the reality", the authority said. Apple Group's taxable profits were recorded through its Irish subsidiaries Apple Sales Internal and Apple Operations Europe, but almost all of these profits "were internally attributed to a 'head office' [theoretically located in Cork, ed.] that existed only on paper", the Commission explained. "Member States cannot give tax benefits to selected companies - this is illegal under EU rules," affirmed the Commissioner in charge of competition policy, Margrethe Vestager. "This is not a fine, this is unpaid taxes to be paid", she added. Apple immediately announced its intention to appeal the decision. CEO Tim Cook penned a letter to Apple's European customers, stating that the company fully complied with Irish laws and condemning the EU's decision as undue interference in Dublin's tax legislation. Ireland, which would theoretically benefit from the payment order, also plans to appeal. Ireland's finance minister, Michael Noonan, said he "disagrees profoundly" with the Commission's decision and affirmed that it leaves him "no choice but to seek Cabinet approval to appeal". The decision was also slammed by the U.S. Treasury department, which recently accused Brussels of acting as a "supranational tax authority" and 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 US and the EU". However, the U.S. itself has been damaged by the practice followed by Apple and other American multinationals of leaving their foreign profits abroad, in order to avoid a tax rate of 40 percent or more. Apple is estimated to have accumulated a fortune of 230 billion dollars all over the world. (AGI). .