The Children's Commissioner says lowering the voting age to 16 is an issue the country needs to genuinely discuss.

Judge Andrew Becroft told a parliamentary select committee on Wednesday morning one of his biggest concerns is that children's voices are not heard.

"You cannot say children are just another interest group, because they are the only group without a voice."

Voter turnout showed young people were the least engaged in New Zealand's democratic process and we needed to do better as a country, Becroft said.


• READ MORE: MPs cool on voting at 16 (2007)

A lower voting age should go hand in hand with civics education to teach young people their rights and democratic responsibilities were important.

"Everything I've seen indicates 16- and 17-year-olds would be up for that responsibility," he said.

"We've got to consider it.

"16- and 17-year-olds are developing, there is much for them to learn, but they're equally capable of expressing views and thinking about our future in encouraging and quite sophisticated ways."

Legislation should be screened to see if it affects children, and if it does, it should be assessed against questions, including what kind of children are affected and whether it will have a detrimental impact, he said.

"Children, by which I mean under 18-year-olds, are 23 per cent of our population and they have no other way of influencing policy," he said.

"If they voted and had a lobby I'm quite convinced our policy for under-18-year-olds would significantly improve."

Children were not "just another interest group", because they were the only demographic who didn't have a voice, Becroft said.

Act leader David Seymour was less enthusiastic about the idea, saying he wasn't keen on expanding the number of non-taxpayers who could vote.

"We've got far too many voters in New Zealanders who don't pay any tax without adding 16 and 17 year olds to the mix."

When pressed, Seymour said he was in favour of restoring the rights of prisoners to vote and believed beneficiaries should be allowed to vote, but was "not in favour of expanding the number of people who pay no taxes and yet vote for lots of spending".

"That's what 16 and 17-year-olds would be, as every parents knows."

Lowering the voting age was floated in 2007 by former Green Party MP Sue Bradford, but the idea never stuck.