The ACT Party says if Donald Trump slashes America's federal tax rate, New Zealand will have to follow suit.

Leader David Seymour has proposed removing the top tax bracket and reducing income tax across all brackets.

The Epsom MP says he will also push for the company tax rate to be cut from 28 percent to 25 percent to promote growth.

At a speech to a business audience in Auckland this afternoon, he said New Zealand will need lower corporate taxes to remain competitive against a lower-tax US.

Seymour said the package is fully costed and will be funded from forecast surpluses along with cuts to waste and corporate welfare.

"We've allowed for $14 billion in spending increases over the next four years, but what we are saying is that Government should not be taxing profitable businesses and giving it to sexy businesses that make good grant applications."

He said the Government can cut taxes and still increase funding to healthcare and education.

Mr Seymour said the tax cuts can actually by funded by cutting "corporate welfare" and other so-called wasteful spending.

"Why should people pay tax to make television, where there's so many things already to watch?" Seymour told Newstalk ZB.

"Does anybody really believe we'd be culturally poorer if we didn't have X Factor?

"I think Jono and Ben are funny enough to succeed on their own terms, but they don't actually need to be subsidised by the taxpayer.

"They're just doing it because, heh, if the Government gives away free money, you'd be crazy not to take it."​

Things David Seymour doesn't want taxpayers paying for:

*Jono and Ben - $1.7 million

*The X Factor - $800,000

*Mastermind - $685,000

*Find Me a Maori Bride' - $590,000

*Gameloft, the designer of My Little Pony - $2.9 million

*Adam and Eve Show - $3 million

*International Business Growth Services - $500 million since 2011

*Anti-trade activist Jane Kelsey's Transcending embedded neoliberalism in international economic regulation - $600,000

*Missing narratives of modern Chinese intellectual history: modernity and writings on art, 1900-1930 - $495,000

*LED screen in the MBIE reception - $147,000

*2500 policy analysts - about $225 million

*Over 5000 managers - about $900 million

*Dubai business expo in 2020 - $53 million

*Cultivating chamber music in Beethoven's Vienna: a study in socio-musicology - $580,000

Finance Minister Steven Joyce has said he doesn't plan to cut tax rates in the budget he'll present on May 25.

He could adjust thresholds as part of a family support package.

Spending watchdog the Taxpayers' Union, which campaigns for tax cuts, was disappointed.

"We were expecting something more ambitious from David Seymour," said executive director Jordan Williams.

"ACT has tied its tax package to measures to reduce corporate welfare - according to our calculations, even if Steven Joyce refused to cut any of that spending ACT's tax relief package is still affordable and within surplus amounts."

- Additional reporting by NZ Newswire