ACT leader David Seymour's work around charter schools could soon fall under the OIA after a bill passed its first reading.

A bill that would make ACT leader David Seymour accountable under the Official Information Act has passed its first reading by one vote.

Labour MP Adrian Rurawhe introduced the Official Information (Parliamentary Under-Secretaries) Amendment Bill, which had its first reading in the House on Wednesday night.

It was UnitedFuture leader Peter Dunne who broke ranks with National and ACT and got the bill over the line - voting in favour of it along with fellow Government support partner, the Maori Party, as well as Labour, NZ First, and Green Party MPs.

Seymour, who is under-secretary for education and responsible for charter schools, as a result of a supply and confidence agreement with National, said it was a "stunt bill".

He questioned why Labour didn't change the bill back in 2005 when former Labour MP Dover Samuels was an under-secretary.

"This is a bill entirely designed to target a particular member: strangely enough, me."

Seymour said the bill was redundant because under-secretaries answered to their Ministers, who were accountable under the OIA.

"The law in achieving its objectives should be proportional and it would be a disproportional application of the law to apply the Official Information Act and requests to under-secretaries."

"All it does is attempt to attack me and while I'm a little bit flattered, I cannot support the bill," Seymour said.

Dunne, himself a former under-secretary, said it was unacceptable to have "some members of the executive covered by the OIA and some not and claim transparency".

He said he was surprised that National opposed the bill.

Rurawhe said his bill was a tiny change to fix an anomaly in the Act and bring under-secretaries to account.

"I've done this because the Official Information Act is one of the few mechanisms of democratic accountability in New Zealand to give taxpayers and New Zealanders the confidence that decisions made on their behalf are right and proper."

"Only a year ago Prime Minister John Key admitted the Government delays releasing official information right up to the deadline if it's in the best interests for them to do so."

The Chief Ombudsman made it clear they weren't allowed to do that but it still happened, he said.

NZ First MP Denis O'Rourke spoke in support of the bill and said it was a "common sense measure".

He accused the Government of having a bad reputation of secrecy and said just this week that had been reinforced by the lack of information around the Trans-Pacific Partnership agreement.

O'Rourke said National not supporting the bill showed it believed it needed to protect under-secretaries due to their "ineptitude" to do the job.

"Mr Seymour falls directly in that category. He's only an under-secretary because of a political deal done with the National Party so it could stay in office. Nobody would dream of putting a wet behind the ears MP like this in an under secretary position," he said.

Earlier in the evening both the Education (Charter Schools Curriculum) Amendment Bill sponsored by Labour's Phil Goff and his colleague Carmel Sepuloni's Social Workers Registration (Mandatory Registration) Amendment Bill were voted down at the first reading.

However, their colleague Clayton Cosgrove got his Keep Kiwibank Bill across the line, again thanks to Dunne who voted in favour of the bill giving it 61 votes to 60.

UnitedFuture's 2011 confidence and supply agreement with National included not selling KiwiSaver so Dunne said it was a "no brainer" to support the bill.