National Party finance spokeswoman Nicola Willis has called on the Government to apologise for the rollout of the cost-of-living payment and said ministers should investigate to find exactly how many ineligible people received the $350 payment.
"I want to see the Government apologise for the rushed way they put this together. They have a moral obligation to answer," Willis said.
The remarks came after Auditor-General John Ryan published findings saying that while the ineligible payments were lawful, they did not demonstrate good stewardship of public money.
"In my view, good stewardship of public money required greater care when designing and implementing the COLP [Cost of Living Payment] – ensuring that the criteria were clear and that the data used by Inland Revenue was adequate," Ryan wrote.
Newly released figures show 4,912 people have opted out of the scheme, while 418 people have repaid their payments. As of Monday, 1.39m people had received the payment with 112,794 eligible people are yet to submit bank details.
The Government continued to defend the $814m scheme on Monday, with Prime Minister Jacinda Ardern saying that it was impossible to design a perfect system for a payment to 2.1 million people.
"There are two alternatives. One would be to have 2.1 million New Zealanders apply. I don't think that would have meant that it would have reached the people who need it most," Ardern said.
"The second option is a tax cut, and it had the potential to have a negative impact - to make inflation worse and would also not be as targeted," she said.
Earlier in the day, Revenue Minister David Parker had unveiled changes to the eligibility checks for the payment, like seeing if people had logged into their IRD portal from an overseas IP address or registered as an overseas student loan borrower.
Now, if the IRD believes people might be living overseas, they will have to prove they are living in New Zealand to receive the payment.
The original eligibility criteria for the payment have not changed, but Parker has tweaked the way that IRD will monitor to make sure that only people eligible for the payment receive it.
Parker said the Government stood by its original decision to not have people apply for the payment, but to pay it to them automatically.
He said the new tests would, ideally, have been included from the start.
"I think there's some fairness in that if we did it again, we would have run those tests from the start," Parker said.
The episode was sparked by a complaint made by Willis to the Auditor-General after a spate of stories about ineligible people receiving the payment.
Ryan looked into the complaint and found that while some ineligible people had received the payment, this was not unlawful on the part of the Government. He did, however, reprimand the Government for not designing a scheme that represented better "stewardship" of public funds.
He also suggested the IRD "identify how many ineligible people have already received payments", and remind people who had already received the payments despite being ineligible, to pay them back.
The findings were in relation to a complaint from Willis after the first round of payments was received by a flurry of ineligible people overseas.
Willis said the Government should take up Ryan's recommendation and investigate how many ineligible people had received the payment, saying the Government had a "moral obligation" to investigate.
"To this day we do not know how many ineligible people have received this payment," Willis said.
"Lessons have to be learned," Willis said.
"What we saw with this payment was a rush and a hurry and a panic with no care for the consequences. Money has gone to people who were not eligible for it," Willis said.
"I want to see the Government apologise for the rushed way they put this together. They have a moral obligation to answer," she said.
Act leader David Seymour agreed with Willis that an investigation was warranted.
He said Parker should commit to accepting all of the Auditor-General's findings on the payment.
"In particular, Inland Revenue should review the payments made to date, identify the scale of incorrect payments, and remind ineligible recipients that they're obliged to repay the money," Seymour said.