The EU Competition Commissioner Margrethe Vestager has prepared a 130-page ruling on Apple's Ireland operations which is due to be released Tuesday. The investigation has been going on for three years.

According to a FT source familiar with the matter, Apple would have to restate its accounts as a result of the ruling. The US company allegedly paid tax at a rate of one percent, well below Ireland’s then official 12.5 percent corporate tax.

The investigation was accompanied by strong warnings from Washington not to fine American companies. The US Department of Justice accused the European Commission of becoming a “supranational tax authority” overriding the tax codes of its member countries. The Obama administration warned the EU that the investigation could “create an unfortunate international tax policy precedent.”

The European Commission accused Ireland in 2014 of dodging international tax rules by allowing Apple to funnel tens of billions of dollars of European profits into the country in return for maintaining jobs. Apple and Ireland reject the allegations and say they will appeal should there be an unfavorable ruling.

The possible multibillion dollar penalty for Apple will be much bigger than fines on other US companies such as Starbucks and Fiat Chrysler. The European watchdog had previously ordered the Netherlands and Luxembourg to recover €30 million in unpaid taxes from the coffee company and car maker.

The biggest penalty to date involved EDF, the French energy group, which was ordered to repay €1.4 billion.

In the worst case should Ireland be forced to collect the unpaid taxes, Apple may have to pay a $19 billion fine.