The process of reclaiming the €13bn (plus interest) that Apple owes following the European Commission's ruling which found that it had been given a sweetheart deal by the Irish government is going to be extremely messy.

While the Government and Apple have appealed against the decision - officials including Finance Minister, Michael Noonan, have repeatedly said that even if the ruling is upheld other European states may be entitled to part of the payout.

Bloomberg reports that the process will also create headaches across the Atlantic. The US Treasury has been a vocal critic of the European ruling. Apple paying European states is likely to create a large foreign tax credit claim for the company in the US.

The US system taxes companies on all of their global income - while offering dollar-for-dollar tax credits to offset payments made in other territories. The newspaper reports that this could result in a €13bn ($14.6bn) loss to the corporate tax take in the US if Apple is ultimately required to pay these back taxes.

This process is further complicated by the fact the US companies can defer their payments on earnings in other territories.

Some $2tn in profits from US companies is currently sitting abroad, awaiting repatriation.

Treasury Secretary Jacob J. Lew has said it is "not appropriate" to seek historic payments from Apple, saying that Europe is "rewriting tax law retroactively, reaching into a tax base that properly should be a U.S. tax base, because it’s US income."

However, there has been debate over whether in Apple's case, where it is judged to have been given an unfair tax advantage, the company should (or would) be eligible to claim these credits. Mr Lew alluded to this issue in an opinion piece in yesterday's Wall St Journal, he wrote, "U.S. companies could claim foreign tax credits against their US tax bill for any tax-related payments to European Union member states."

Skin in the game...

Meanwhile, Germany's Minister of Finance Wolfgang Schäuble has said that while he would "naturally" welcome an Apple tax windfall in Europe, he believes it's extremely premature for countries to be expecting extra cash from the tech giant.

Schäuble said that he thinks "the expectations being built up there are somewhat previous" – or to put it in more flowery language "you should never divvy up the bear skin before you've taken out the bear."

The finance minister was very much in favour of the Apple "bear" being taken out. A critic of Ireland's corporate tax model, he welcomed the European Commission's finding that Apple owed €13 billion in back taxes.

The appeal against the Commission's ruling is likely to be a drawn-out affair that will take several years to complete.