The Irish government said it will consider the legal grounds of the European Commission's appeal over a court decision not to order Apple to pay back 13 billion euros (£11.6 billion) in taxes to the Repubilc of Ireland.
The country's finance minister said that the Republic has always been clear that the correct amount of Irish tax was paid and that the Republic provided no state aid to Apple.
The EU's General Court in Luxembourg ruled in July that the commission wrongly declared in 2016 that Apple was given illegal state aid when it struck a low tax rate agreement with Irish authorities.
Today, the European Commission said it "respectfully considers that in its judgment the General Court has made a number of errors of law".
Executive vice president Margrethe Vestager said for this reason, the Commission is bringing this matter before the European Court of Justice.
An appeal to the bloc's highest court must be on a point, or points, of law.
The appeal process could take up to two years to complete.
Minister for Finance Paschal Donohoe said he notes the European Commission's decision to lodge an appeal.
Mr Donohoe added: "Ireland has not yet been served with formal notice of the appeal.
"When it is received, the government will need to take some time to consider, in detail, the legal grounds set out in the appeal and to consult with the Government's legal advisers, in responding to this appeal."
The 13.1 billion euro is being held in an escrow account, meaning the proceeds cannot be released until there has been a final determination in the European courts over the validity of the commission's decision.
The EU Commission had ordered Apple to pay for gross underpayment of tax on profits across the European bloc from 2003 to 2014.
The commission said Apple used two shell companies in Ireland to report its Europe-wide profits at effective rates well under 1%.
The Republic's open economy is based on low corporate taxation and other incentives to attract multinationals.
In Apple's case, it was significantly below the standard 12.5% imposed on corporations.
Apple said that, from 2003 to 2014, it paid 577 million US dollars (504.6 million euro) in tax on profit generated in the country, in line with the tax laws in Ireland.
Apple said the case was never about how much tax it pays but where it is required to pay.
The company said: "The appeal will not alter the factual conclusions of the General Court, which prove that we have always abided by the law in Ireland, as we do everywhere we operate."
