Update 10.15pm: TDs approve Government decision to appeal Apple tax ruling by 93 votes to 36.
Update 9pm: The Finance Minister says there was absolutely no political input into any arrangements between Apple and the Revenue Commissioners.
Michael Noonan says the tax agency always acts independently and was not directed by the Fianna Fáil government of the day.
He was speaking as votes on a series of motions regarding an Apple tax appeal began in the Dáil.
The Minister says there is no suggestion at all of politicians being involved in Apple's deals.
"I think that I should say first that there is no suggestion of any political input into those decisions by the government of the day, the Revenue Commissioners are independent and they decided on independent grounds that this was the decision."
Update 6pm: A Cabinet Minister has called Apple's tax setup in Ireland “ not ethical” - but insists it was still legal.
Katherine Zappone admitted to TDs she found it difficult to support the Government's appeal to the €13bn ruling.
However, she said that she is supporting the appeal for different reasons than her Cabinet colleagues.
“The dealings with Apple, while they may be legal, are certainly not ethical,” she said.
“And indeed, my support is for reasons which are different from those of some of my Cabinet colleagues and, I would suggest, different to some of those in the Opposition.
“Our response to the European Commission decision and its fallout must have a strong tax justice foundation.”
The Dáil has been debating the appeal all day and is due to start casting votes on it at around 8.30pm this evening.
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Update 4.30pm: The Taoiseach Enda Kenny says Ireland has to send a clear and strong response to the profoundly wrong and damaging Apple tax ruling.
Mr Kenny says the Government is adamant nothing illegal was done and Apple didn't get any special treatment.
He said: "The Commission's conclusion that Ireland granted undue tax benefits of up to €13bn in a way that transgressed EU state aid rules is so profoundly wrong and damaging that it demands an immediate, a clear and a strong response."
Today's Dáil debate is about rubber-stamping the decision made by Cabinet last week.
The Taoiseach attacked Brussels for what he said was a profoundly wrong and damaging ruling that couldn't be left unchallenged
"This is our sovereign right as a nation and we object to any attempts to restrict us making policies for our own people."
Though Green leader Eamon Ryan - who is against an appeal - warns against such talk.
Mr Ryan said: "We will not move on by setting all our guns aimed at Brussels or at the rest of Europe and pretending that we are white as the driven snow."
Sinn Féin and some opposition parties believe we should take the money and use it, but Fianna Fáil leader Micheál Martin says such an attitude would see other companies leave Ireland.
Mr Martin said: "It is a clear and present threat to Irish workers in the private sector, and the funding they generate for the services we all rely on."
Richard Boyd Barrett of People Before Profit claimed Ireland was facilitating tax evasion, and questioned why there was a sudden drop in taxable income of corporations, "from €56bn in 2007 to €37bn."
Independent TD Mattie McGrath is also against the appeal, adding there is reputational damage.
Mr McGrath said: "We've a lot of washing to wash out here, and we've good dry days at the moment with sunshine for drying as well, and there is very much dirty linen to be washed."
The vote takes place at 8:30pm tonight - Stephen Donnelly continuing the break from his former Social Democrat colleagues - he will abstain, while they vote against.
Update 1.40pm: The appeal is opposed by Sinn Fein, the Anti-Austerity Alliance-People Before Profit group and the Greens.
Sinn Fein finance spokesman Pearse Doherty said Apple made €104bn of tax-free profits over 10 years from 2003 by using Irish-incorporated firms Apple Sales International and Apple Operations Europe to book sales outside the US and move money into a "sort of untaxed Bermuda triangle".
"For too long this state has had its head in the sand when it comes to the global moves towards tax transparency and fairness," he said.
"This is our money."
Mr Doherty said it was a "cynical lie" to suggest that Brussels was attacking Ireland's corporation tax rate and that the case was fundamentally about equal tax treatment for all.
Labour leader Brendan Howlin, who supports the appeal, said the ruling by Europe was troubling.
"They know well that this is a problem that has its origins in the interaction of different tax codes on a global level," he said.
"And yet they seem to believe that Ireland, a small nation, should carry the reputational hit for correcting this problem."
Update: 10.50am: Enda Kenny has said that the Apple judgement will "damage" not just Ireland but other European countries and turn investors away if tax rules a decade old can be revisited writes Irish Examiner Political Correspondent Juno McEnroe.
Defending Ireland's tax laws, the Taoiseach said that real reform of tax laws were underway in Europe. But he led a strong attack on Brussels, saying: "It is not true that Apple was provided with more favourable treatment than others. There was no preference shown. The law was applied fully and appropriately, and Apple paid its taxes due in Ireland."
Appealing the EC €13bn tax decision would also send out an Important message for business and investors, he told this morning's Dail debate.
Overturning the tax ruling against Apple was essential but not just for Ireland, Mr Kenny declared: "The Commission’s decision has done great damage to that goal, and not just in Ireland’s case.
"If the situation in Europe is to be that tax rulings can be revisited and set aside by the Commission even decades after the event, investors will simply not know where they stand when they locate in Europe.
"Have no doubt about it, that uncertainty will be weighed carefully in the minds of investors and will count against European countries – and not just Ireland - when they compete for mobile investment unless this decision is challenged and overturned and certainty is restored."
Earlier: Finance Minister Michael Noonan has opened the Dáil debate on the Apple judgement saying “aggressive tax” practices are no longer sustainable or acceptable writes Irish Examiner Political Correspondent Juno McEnroe.
Amid claims the day-long emergency Dáil debate is a sham, he defended the decision to hold it saying the EU judgement on Apple’s €13bn tax bill was a landmark moment.
But Opposition TDs are up in arms over the fact that the full 130-page judgement from the European Commission is not being released for the debate.
Mr Noonan said this morning that, up until the decision from Brussels in recent days, that he had no idea about what the European Commission would decide.
Brussels had still also yet to publish its final decision on the tax liability for the tech giant.
The basis for the appeal against the Apple ruling is, according to the document circulated by the Department of Finance to TDs for today’s debate, to defend Ireland’s tax system, to provide tax certainty to business and to challenge “the encroachment of EU state aid rules into the sovereign member state competence of taxation”.
The State has a period of two months and 10 days to bring an appeal. But the appeal may take several years.
Despite the appeal, Ireland is required by law to recover the alleged State aid from Apple, in a similar manner to how the Netherlands has been required to recoup taxes from Starbucks in a similar case. The Apple case involves recouping tax payments over a ten year period up until 2013. The calculated €13bn is also subject to interest. However, Ireland is not subject to any fines.
The Dáil debate today is scheduled to run until 8pm this evening, followed by which votes will be held on amendments and the government motion for the appeal.
Mr Noonan also told the Dail this morning that the Government "did not give favourable treatment" to Apple and does not do tax deals with taxpayers.