The cost of fighting the European Commission's ruling that Apple owes significant back taxes in Ireland is starting to add up for the State. 

It came to almost €270,000 in the last three months of 2016, with €142,186 being paid to corporate law firm William Fry, according to The Irish Independent.

If the ruling is upheld, Apple's tax bill is expected to be close to €13bn.

However, this figure is still being calculated. Commenting on the process Finance Minister Michael Noonan said, "To find the legal basis of the exact amount when the sum is as big as €13bn - that takes a little time."

"We're agreeing the basis of the calculation with the Commission, but it's work in progress," he added.

European Commissioner for Competition Margrethe Vestager criticised Ireland last week over the length of time it is taking to recover unpaid Apple tax.

"The calculation of the exact amount is a very difficult process and we're working closely with the Commission and if the Commission are a little patient, we'll collect the money," Mr Noonan said yesterday.

Both Apple and the Irish Government have launched appeals against the EU's ruling which judged that Ireland had offered a 'sweetheart' tax deal to the US tech firm.