TECHNOLOGY giant Apple has warned its shareholders that it may have to pay back tax to Ireland following a European Commission State-aid probe.

It also told investors in the company that such a move could hit Apple's bottom line.

While it is not clear how much money could be involved, Apple has made nearly $70bn in profits from operations that are not US-based and haven't been subjected to corporation there.

Some of these operations are "organised in Ireland."

The 10k statement filed with the US Securities and Exchange Commission on October 27, says: "for example, the European Commission opened a formal investigation to examine whether decisions by the tax authorities in Ireland with regard to the corporate income tax to be paid by two of the Company’s Irish subsidiaries comply with European Union rules on state aid.

"If the European Commission were to take a final decision against Ireland, it could require changes to existing tax rulings that, in turn, could increase the Company’s taxes in the future.

It added that the Commission could also require Ireland to recover from the Company past taxes reflective of the disallowed state aid.

It also warned that such a move could hit Apple's results in the future.

"If the Company’s effective tax rates were to increase, particularly in the U.S. or Ireland, or if the ultimate determination of the Company’s taxes owed is for an amount in excess of amounts previously accrued, the Company’s operating results, cash flows and financial condition could be adversely affected," according to the statement.

The Government here has recently rowed back on tax breaks for multinationals in a bid to improve Ireland’s reputation.

In Budget 2015 it announced an end to the so-called “double Irish” and plans to introduce a “knowledge box” as an alternative measure –it allows companies to lower the taxes on patents profits.

Online Editors