National's finance spokesperson Nicola Willis has explicitly admitted she doesn't know the impact her party's housing policies will have on house prices.
And Newshub can reveal the cost of one of them might blow out from what she budgeted for - leaving her tax plan with another hole.
On Thursday, three economists from across the political divide provided analysis showing National would be $500 million short of what it thinks it would bring in each year from taxing foreign buyers.
"Their plan has so many holes in it," Labour leader Chris Hipkins said. "It's got more holes than a block of Swiss cheese."
During Queenstown's great finance debate on Thursday night, Willis was under pressure to release her numbers and admit whether the policy would push up house prices.
She also admitted she was unaware of the impact of shortening the bright line tax and reversing interest deductibility rules.
"I don't know what it'll do to house prices," she said.
Asked by reporters after the debate how much interest deductibility and bright-line tests would push up the price of houses, Willis said: "We don't think it will affect the price of houses."
But Newshub has obtained new figures showing the interest deductibility reversal may cost a lot more than National has planned for.
It's budgeted at $2.1 billion over four years but that was costed off publicly available projections.
New projections, prepared for the minister in November and released to Newshub under the Official Information Act, show it could actually cost about $350 million more.
Labour under fire for errant spending
At the debate on Thursday, the Queenstown audience was much more taken by wasteful spending jabs aimed at Labour by Willis.
And National on Friday took aim at the Ministry for Pacific Peoples after revelations it spent $52,000 on breakfast meetings promoting Labour's budget.
National leader Christopher Luxon said it was an "extravagant waste of money during a cost-of-living crisis".
But Hipkins said he didn't think New Zealand's Pacific community "should be excluded from being able to hear about the budget".
The same ministry recently came under fire for throwing a $40,000 leaving party and ACT leader David Seymour was slammed for joking he wanted to send Guy Fawkes in.
At the debate on Thursday night, Seymour made another so-called joke about what might happen to the ministry if National and ACT are elected.
"I guess Nicola might have to increase their security budget," he said, laughing about threats to public servants.