Shane Jones has accused National of "fearmongering" over a possible capital gains tax while debating with MP Paul Goldsmith about the Provincial Growth Fund.
On TVNZ1's Q+A, Mr Goldsmith said the capital gains tax would dominate political discussion for the first half of next year.
"Because [the Government] want more taxes, major new taxes on the entrepreneur and the savers in this country.
"A good place to start would be to stop wasting money."
Last week, the National Party promised to repeal any possible capital gains tax if it is elected into power in the next general election.
When asked if NZ First would support a capital gains tax, Mr Jones said, "we're going to wait and see what Dr Cullen and his group of grandies come up with", in reference to the tax working group headed by Sir Michael Cullen.
"All this scaremongering aside... it's obvious fearmongering. The reality is when we set [the Provincial Growth] Fund up we look New Zealanders straight in the eye and we said we're going to go to the regions, we're going to back your proposals. We're not going to be petty and capricious."
Q+A host Corin Dann asked if Mr Jones was having a negative impact on business confidence, "unsettling the business community by wading in and publicly attacking chief executives.
Earlier this year, Mr Jones came out swinging at Fonterra and Air New Zealand, saying he was "thoroughly unimpressed" with Air New Zealand's treatment of regional New Zealand after some flights were axed.
"They earn these huge, stratospheric salaries. They have their own ideas as to how the economy should be run," Mr Jones told Q+A.
"If they put their head up and participate in a political debate, they should expect to receive political fire."
"They live a highly privileged lifestyle, so don't come the cry-baby with me, they want to impose their views on the rest of us."
During the debate, Mr Jones defended the decision to start extending loans from his billion dollar growth fund to private businesses.
He said public private partnerships were not new.
However, Mr Goldsmith said the move was a strange extension into ordinary business practices.