Labour leader Chris Hipkins says Christopher Luxon is incompetent and is dismissing National's attacks over the opposition party's tax plans as hysterical desperation.

Speaking to media after the prime minister and transport minister announced a detailed business case on a second Auckland harbour crossing, Hipkins was asked if Labour would bring in a new tax on streaming companies such as Netflix or bring back the so-called ute tax.

He had a simple answer to both: "No."

It followed National finance spokesperson Nicola Willis on Sunday calling for Hipkins to clarify his position on the two taxes.

She said Labour broadcasting and media spokesperson Reuben Davidson was "proposing to introduce a levy on streaming services that would jack up the price Kiwis pay for Netflix and other streaming services".

Willis also pointed to an NZ Herald report showing Michael Wood, who re-entered politics after resigning from Cabinet in 2023, had been talking up the Clean Car Discount scheme labelled by National as a 'ute tax' as a policy win he achieved.

However, the article does not indicate Wood planned to bring back the scheme, which granted rebates for imports of low- or zero-emission vehicles paid for by imposing a fee on high-emitting ones.

National campaign chair Simeon Brown on Monday afternoon released another statement during the Waitematā announcement saying Hipkins had been "silent" on both ideas.

Brown said Hipkins "has had 24 hours to rule out a streaming tax and a ute tax, and all we have heard is radio silence".

"We already know Labour and their mates are planning to hit Kiwis with nine new taxes to fund their $18 billion hidden bill. Information revealed by National yesterday shows they appear to be planning two more, with a streaming tax and a ute tax. That would be 11 new taxes.

"These are not backbench thought bubbles. One is a former Cabinet minister. The other is Labour's broadcasting and media spokesperson announcing policy in his own portfolio... he has had a full day and said nothing. If he cannot rule out both taxes on his media round tomorrow morning, New Zealanders can only assume Labour will be campaigning on them."

Those "nine new taxes" include three from Labour, including the capital gains tax policy, a reinstated 3 percent digital services tax on tech giants, and the scaling back of National's Investment Boost policy.

The remaining taxes are policy pitches from the Greens, Te Pāti Māori and Opportunity, including a 45 percent top tax rate, inheritance tax, gift tax, removing interest deductibility from rental properties, an assets tax and a land tax.

Hipkins, who has repeatedly ruled out implementing tax policies from other parties, said the statements from National were "just desperation".

"Simeon Brown is getting more and more hysterical by the day. I guess if I was looking at internal polling numbers like the sort that he's looking at I'd be getting a bit worried about that as well, but that doesn't mean that he can make up policy on behalf of the Labour Party."

However, those other parties have typically denied such policies could be ruled out before negotiations to form a government.

Willis had also pointed to Labour's Willie Jackson telling Ryan Bridge's TODAY programme Labour would show respect to its prospective coalition partners and, when asked what percentage of a land tax they could accept, saying "who knows".

Hipkins said Jackson "could have been clearer" and pointed to Jackson later in the interview saying he was not open to a land tax.

"Nobody's perfect in every answer that they deliver, including me. Every now and then, you say something, and you think 'gosh, I could have been clearer'," Hipkins said.

He said another Opportunity Party policy to cut 2000 public servants by scrapping benefits in favour of a universal basic income, which would arguably take less work to administer, was "incredibly unrealistic".

Hipkins indicated he would not be meeting with Opportunity leader Qiulae Wong ahead of the election to sort either matter out.

"We'll see what the voters dish up, but we won't be meeting... no doubt we'll run into each other. You know, probably we may well end up on a stage together at some point with leaders' debates and those sorts of things, but I don't have any intention to have formal sit-down meetings."

With Luxon having announced a policy to hold a referendum on MMP if re-elected, Hipkins said the system was "by and large" working well and "I don't intend to change it".

"New Zealanders have repeatedly chosen MMP, they were given a referendum as recently as ... was it 2011? And convincingly decided to keep it."

He dismissed the referendum idea as incompetence on Luxon's part.

"If you're an incompetent prime minister, no electoral system is going to help you do a better job of running the country. Christopher Luxon has made an absolute hash of running his coalition. That's not MMP's fault. That's Christopher Luxon's fault."

However, reporters were soon questioning Hipkins' own competence after he revealed he had not heard or seen a briefing on any of Luxon's regular Monday morning interviews.

"I'm not watching every media interview that everyone in government does, including the prime minister. Generally, I get an update on them, but I haven't this morning. I haven't from this morning," he said when asked if the opposition leader should be across things like that.