The European Union's tax commissioner will still present proposals this year for a pan-EU method of calculating company taxes despite Ireland's rejection of the Lisbon Treaty partly.
"It will be during the French presidency of the EU," the commissioner, Laszlo Kovacs, said. France takes over the six-month rotating EU presidency in July.
Mr Kovacs said an impact assessment on the proposal was being finalised.
Many cross-border companies would welcome a simpler way of calculating taxes, but Ireland has long argued that such a move would be the first step towards imposing harmonised corporate tax rates on EU states.
Ireland's economic strength has been linked to the low corporate tax rate, and the No campaigners had said the Lisbon Treaty, aimed at reforming EU institutions, would dent the Government's sovereignty in tax matters.
"All those that campaigned against the Lisbon Treaty with slogans that Ireland will lose tax sovereignty were simply telling lies," Mr Kovacs said.
The European Commission had already delayed presenting its common consolidated corporate tax base (CCCTB) proposal until after the Irish referendum to avoid undermining the Yes campaign.
But Mr Kovacs appeared to rule out further delay as EU leaders scramble for a solution to the No vote while preserving the changes the treaty would bring.
"There is no reason to change our plans concerning tax policy initiatives. The CCCTB is in the pipeline," Mr Kovacs said.
The Lisbon Treaty, if it came into force, would not change the current situation whereby unanimity among the 27 EU states is needed to adopt any tax measures, including the CCCTB.
"The Lisbon Treaty would not change anything as far as tax is concerned," Mr Kovacs said.