UPDATED 11.42am  The European Union has made its biggest ever tax ruling on a single company, ordering Apple to cough up 13 billion Euro, which is approximately $20 billion NZD.

LISTEN ABOVE: Jack Tame speaks to Rachel Smalley about Apple's tax bill

It may now spark a row over how Europe treats companies based in the United States.

The European Commission, which administers EU law, said Ireland gave illegal state aid to Apple.

It said it helped the tech giant artificially lower its tax bill for more than two decades.

Apple paid tax at one percent or less on profits from its subsidiaries in Ireland.

in 2014, that percentage had dropped to 0.005 per cent, which means Apple paid just 50 Euros in taxes for every million Euros it made.

That's well below the 35 per cent top rate of corporate tax in the US, and 12.5 per cent in Ireland.

Ireland, where Apple is headquartered, is arguing against the ruling.

The Finance Minister Michael Noonan is arguing that they want Ireland to remain an attractive place for long-term, substantial investment.

He said the Irish government is taking a bit of a punt, saying the jobs are worth more to voters than a $13 billion investment would be.

Wall Street has been unsettled by the European Commission's ruling against Apple.

Stocks in the U.S have drifted lower in trading as investors digest the news.

Apple shares have dipped to 0.67 per cent - that's USD $106.10 per share.

New Zealand tax officials would be looking at the EU tax ruling on Ireland and the Apple company to see if there were any lessons for New Zealand, Prime Minister John Key said this morning.

"But every country's tax rules are different...I'm sure our officials will go and have a look and see if there are any learnings they can take out from that and in the meantime continue the work we are doing with the OECD."

Talking to reporters in Wellington today, Key said New Zealand expected multinationals to pay their fair share of tax and it was part of the OECD working group to see if potential loopholes could be tightened.

He said Apple in New Zealand was probably paying its fair share of tax "if you look at the current tax rules and the way they intersect with the different tax rules around the rest of the world."

"I don't have any advice that they are doing anything illegal, that's for sure.

"But the question is whether the mismatch of all of those rules is something these multinationals can arbitrage, and if they are, then we would say on balance that's not fair even if it's legal.

"That's really what the OECD is trying to do - to try and say 'well collectively, can we all hold hands and make sure that those loopholes disappear.

"We expect a New Zealand company to pay its fair share of tax; we expect a New Zealand citizen to pay their fair share of tax. Should we expect a multinational to play by different rules?"

Commenting on the Australian Government's new policy to tax multinational companies caught trying to divert profits overseas for tax avoidance at 40 per cent instead of 30 per cent, Key said the advice he had had was to move on the multinational front.

"We are a bit dubious about whether what has been announced in Australia will actually work but we will certainly have a look at it."