US Treasury Secretary Steve Mnuchin has officially announced that the US will reduce its corporate tax rate to 15% from the current maximum of 35%.
He also said the US will introduce a one-time tax rate to incentivise companies to repatriate their profits to the US.
Mr Mnuchin said the rate of that special one-time tax offer is still being worked out, but it will be "very competitive".
The US will also introduce a "territorial tax system" for business meaning companies will only have to pay tax on the profits earned in the US, and will not be subject to a worldwide filing requirement.
He said he was meeting constantly with members of the House of Representatives and Senate and was hopeful that they would get the legislation required to introduce these changes passed "this year".
Earlier Mr Mnuchin said the administration hopes to push the reform through Congress as quickly as possible.
But President Donald Trump's plan for a major new tax reform will face politicians already sharply divided over fiscal policy and rising deficits.
The Department of Finance said it will monitor the announcement and that the exact implications of US tax reform for Ireland, and the rest of the world, will depend on the exact nature of any changes which are ultimately agreed.
Analysts have said cutting the marginal corporate tax rates by 20 percentage points could add as much as $2 trillion to the deficit over a decade.
The administration believes growth will bring in revenues to make up the difference - a calculation known as "dynamic scoring" - but economists say this is not supported by evidence from prior efforts.
Mr Mnuchin also said the administration plans to simplify the process by which Americans declare their income and pay taxes.
The "objective is simplifying personal taxes. For most Americans, we think they should be able to do their taxes on a large postcard," he said today.
The US president had also proposed offering multinational businesses a steep tax break on overseas profits brought into the US.
Mr Trump is also expected to call for a sharp cut in the top rate on pass-through businesses, including many small business partnerships and sole traders, to 15% from 39.6%, an administration official said.
He will propose cutting the income tax rate paid by public corporations to 15% from 35%, and allowing multinationals to bring in overseas profits at a tax rate of 10% versus 35% now, the official said.
Mr Trump's proposal will not include a controversial "border-adjustment" tax on imports that was in earlier proposals floated by Republicans as a way to offset revenue losses resulting from tax cuts.
His tax blueprint will fall short of the kind of comprehensive tax reform that Republicans have long discussed, and serve chiefly as a guidepost for politicians in the House and Senate.
Mr Trump sent Mr Mnuchin and National Economic Council Director Gary Cohn to Capitol Hill yesterday to brief politicians on the plan.
Mr Mnuchin has been leading the administration's effort to craft a tax package that can win support in Congress, although the proposals would have a long way to go before becoming law, even with Republicans in control of both the House and Senate.
He has said the cuts will pay for themselves by generating more economic growth but many politicians are certain to question these claims.
Mr Trump also may cap the individual top tax rate at 33%, repeal the estate and alternative minimum taxes and cut taxes for the middle class, analysts said.
A senior White House official said Mr Trump would like to see Congress pass tax reform by the middle of autumn.
