National leader Simon Bridges has pledged to fight tax recommendations "every step of the way".
Today the Tax Working Group released its recommendations to the coalition government which included a capital gains tax (CGT) covering holiday homes, land, most shares and business assets, including goodwill.
People's primary residence would be excluded, as would the land beneath it, earnings from KiwiSaver and personal assets like cars, bikes and boats.
The tax would be levied at the marginal income rate of the person selling the assets.
A capital gains tax is a tax on the profit from the sale of an asset.
Check out RNZ Tax Working Group coverage
- The Tax Working Group unveils final report, recommends a capital gains tax
- Look back on RNZ's live coverage of reaction to the recommendations
- The Tax Working Group to release findings: What to expect
Mr Bridges said the the tax recommendations were "an assault on the Kiwi way of life".
A raft of new taxes targeting hard-working New Zealanders were among the recommendations, he said.
"This is an attack on the Kiwi way of life. This would hit every New Zealander with a KiwiSaver, shares, investment property, a small business, a lifestyle block, a bach or even an empty section," Mr Bridges said.
"For farmers, who are the backbone of our economy, this is a declaration of war on their businesses and way of life. They would pay to water their stock, feed their crops and even when they sell up for retirement.
"Labour claims this is about fairness, but that's rubbish. The CGT would apply to small business owners like the local plumber, but not to investors with a multi-million dollar art collection or a super yacht who won't pay a cent more.
New Zealanders already paid enough tax and a National government would repeal a capital gains tax.
This Tax Working Group report is an assault on the Kiwi way of life. I will fight it every step of the way.— Simon Bridges (@simonjbridges) February 20, 2019
National Party finance spokesperson Amy Adams said the recommendations would hurt hard working New Zealanders.
Cullen’s Tax working group has recommended a massive tax grab with 8 new taxes including a Capital Gains Tax. This will hammer our economy and hurt hard working New Zealanders— Amy Adams (@amyadamsMP) February 20, 2019
"The new taxes proposed today will create a compliance mine field, massive distortions in the market and weaken our international competitiveness at the very time the government acknowledges the international economic risks are growing," Ms Adams said.
"It would add significant complexity to our relatively simple tax system, likely exempt Iwi assets, require all eligible assets to be re-valued within five years and further drain New Zealand's already shallow capital markets."
Earlier, Finance Minister Grant Robertson said the government would take a "measured approach" in its response to the recommendations.
It would not be "throwing the baby out with the bathwater" as it looks at what recommendations it might adopt, he said.
The government would seek technical advice on addressing some of the elements of the tax system deemed to be unfair by the Tax Working Group, but Mr Robertson said it was "not bound" to accept the whole report.
However Taxpayers' Union Executive Director Jordan Williams said the measures would be a "blatant revenue grab".
The Employers and Manufacturers Association said the key issue in the Tax Working Group's proposal was that any gains from such a broad-based capital gains tax would be eaten up by administration and other costs, leaving little revenue.
The Federated Farmers is also opposed saying that a capital gains tax is a "mangy dog, that will add unacceptably high costs and complexity".
"There is nothing in the Tax Working Group's final report, released today, that persuades us otherwise," Federated Farmers spokesperson Andrew Hoggard said.
He said it is notable that even the members of the working group could not agree on the best way forward, with three deciding a tax on capital gains should only apply to the sale of residential rental properties and the other eight recommending it should be broadened to also include land and buildings, assets, intangible property and shares.
Three of the working group members from Business New Zealand including its chief executive, a former Bell Gully tax partner and a former Inland Revenue Deputy Commissioner want to see a more limited capital gains tax.
Canterbury Employers' Chamber of Commerce said key areas of the report were "disappointing'' and would have a significant impact on small and medium-sized businesses.
ACT Party leader David Seymour said a capital gains tax represents double taxation.
"It is wrong to idolise envy and punish success."
The Green Party welcomes the report.