Labour has asked the Auditor-General to investigate the practice of some schools charging parents to participate in out-of-zone enrolment ballots highlighted by the Weekend Herald.
Three schools have been identified by the Herald, Mt Albert Grammar, Auckland Grammar School and Cornwall Park District School which charged $30, $50 and $75 respectively.
Cornwall Park refunded parents that had paid after receiving a reprimand from the Ministry of Education.
But Auckland Grammar and Mt Albert Grammar claimed they were doing nothing wrong - that it was a donation, it was not compulsory and there were administration costs involved in running the ballots.
Labour's education spokesman, Chris Hipkins, said some parents believed they would be disadvantaged if they did not pay the fee.
"The right to a free education is enshrined in law," he said.
"It is patently unfair that some parents are being charged a fee to participate in a ballot which is a normal activity for school staff."
He said it was evidence of the financial strain that state school were under, 41 per cent of which were in deficit.
He said he had asked Auditor-General Lyn Provost to consider whether the practice undermined the longstanding Kiwi value that all children must have equal opportunities.