The offices of the Prime Minister and the Social Development Minister were both informed about the superannuation overpayment to New Zealand First leader Winston Peters, as investigations continue into the leak.
Mr Peters has confirmed his fortnightly pension had been overpaid for several years and when he was notified in July he repaid it within 24 hours. He has not disclosed the sum but said it was less than the $18,000 reported in some media.
Both the Ministry of Social Development (MSD) and Inland Revenue (IRD) are trying to find the source of the leak and Mr Peters plans to lay a complaint with the Privacy Commissioner.
Mr Peters has told RNZ that he believed Inland Revenue was to blame for the privacy breach. Pension entitlements are calculated by Work and Income but payments are administered by the IRD.
The office of Social Development Minister Anne Tolley said she was told by the MSD chief executive on 31 July, under the "no surprises" policy, under which ministers are advised in advance about issues potentially affecting their departments. She received an update two weeks later that the matter had been dealt with to the ministry's satisfaction.
A spokesperson for Prime Minister Bill English said his office's chief of staff, Wayne Eagleson, was informed by the Social Development Minister, also under the no-surprises policy, but passed the information onto no-one else.
"The minister indicated that MSD had advised that the matter had been dealt with to the satisfaction of MSD. On that basis Mr Eagleson decided that it was not necessary to advise the prime minister or anyone else in the office on the matter."
Both offices have denied any leak came from them.
State Services Minister Paula Bennett was also briefed about Mr Peters' situation by the State Services Commission.
Revenue Minister Judith Collins was not briefed as tax law prohibits the minister being informed, her office said, and the matter was not leaked by the minister or anyone from her office as neither knew of it before it was raised by the media.
ACT leader David Seymour told Morning Report he found it "very very odd" that personal information on Mr Peters would end up with Mrs Tolley.
"Usually no surprises is more about, an OIA [Official Information Act request] has been filled out and the following information is going to be released to the public and you need to know because it's going to be public soon."
But Mr Seymour said the whole matter could be put to rest if Mr Peters released all the information he had on the subject.
Labour Party leader Jacinda Ardern said she was not surprised MSD officials informed Mrs Tolley, but she did not believe the minister would reveal such private information.
But she was concerned that the information had found its way into the public domain.
"We have a duty of care when we are in positions of responsibility," she told Morning Report. "I wouldn't instinctively think that Anne Tolley would be someone who would release that private information, because of that duty of care."
National Party leader Bill English said, whoever was to blame, the privacy breach was a concern. "These are personal details of people's lives and people expect them to be treated confidentially."
Privacy Commissioner John Edwards said a breach relating to tax information could result in a criminal prosecution. Mr Peters could be eligible for compensation from both organisations if either was found to have breached his privacy and it caused him harm.
In a statement the Ministry of Social Development said it had no reason to believe any personal, private information of Mr Peters has been passed to a third party.
"But given the high-profile nature of this case, it will be undertaking some routine checks to make sure," the statement said.
Inland Revenue acting commissioner Cath Atkins said the department took such allegations seriously and was "looking into them".
"Inland Revenue has very clear code of conduct requirements that all our staff are aware of and very strict tax secrecy obligations in respect of individual taxpayer affairs."
United Future leader Peter Dunne, a former Revenue Minister, said he would be "astounded" if the leak had come from IRD.
"I know when I was a minister it was very difficult to get legitimate taxpayer information from them, let alone anything scurrilous of this type," Mr Dunne said.
At a Northland candidates meeting in Mangawhai last night, locals said the story was a beat-up and that Mr Peters had done nothing wrong .
"I think we [should] leave the poor guy alone. He's not the only one who's ever found himself in that position and if he wasn't in politics we wouldn't be bothering about him," one voter said.
"The people in the media will pick on any little thing they can, and if the poor man didn't know he was being overpaid - and even if he did it's only a small amount - but he didn't know, and he paid it back straight away, why don't we leave him alone," said a second.
"I just think it's a load of crap," another Mangawhai voter said. "I think it's just another one of those things that media and whoever are on the bandwagon - and yeah, by all means pick on him, he's got the answers for you."