A US plan to change how global companies are taxed could have "very meaningful and significant effects" in Ireland, the country's finance minister has said.
The Biden administration is proposing a global minimum corporation tax rate.
That could undermine Ireland's 12.5% corporation tax rate as a way to attract investment.
Pascal Donohoe said he did not believe Ireland was being specifically targeted by the US.
In an interview with Irish broadcaster RTÉ, Mr Donohoe said: "I've been saying this moment has been coming for years, it's now happening, and it will have consequences.
"It could have a very meaningful effect, and significant effect, on how we conduct corporate tax policy in Ireland.
"It has the potential to have a very big impact on where tax is collected."
Level playing field
The US Treasury Secretary Janet Yellen has suggested a 21% minimum global corporation tax rate.
"We are working with G20 nations to agree to a global minimum corporate tax rate that can stop the race to the bottom," she said in a speech earlier this month.
"Together we can use a global minimum tax to make sure the global economy thrives based on a more level playing field in the taxation of multinational corporations."
Essentially that would mean if a company paid tax at the lower Irish rate, then the US (or other countries) could top up that company's tax in their jurisdiction to get it to the global minimum.
So if a US company had a presence in Ireland primarily for the tax advantage, that advantage would disappear.
This is a matter of urgency for the Biden administration, because it is planning to raise corporate taxes at home and would prefer not to see more tax revenues leaking to other countries.
The Biden proposals have reinvigorated work that is being led by the OECD (Organisation for Economic Co-operation and Development), an intergovernmental economic organisation.
It began a project known as Base Erosion and Profit Shifting (BEPS) in 2013, which aims to mitigate tax loopholes that currently allow companies to shift profits from higher tax countries to lower tax countries like Ireland.
Ironically Ireland has been a beneficiary from some of the early outcomes of the BEPS project.
The country's corporation tax receipts have soared from about €4bn (£3.5bn) in 2013 to around €12bn (£10.5bn) in 2020.
This is because there is a greater emphasis on companies declaring their profits in the location where they have real operations or activities.
US multinationals do have significant operations in Ireland across IT, pharmaceuticals and medical devices.