The surging cost of living has exposed inequalities in New Zealand at a time when the local economy is doing well. Growth rates are well above Australia's and the OECD average.

The Kiwi economy is close to full employment, with unemployment rates at an 11-year low of 3.9 per cent.

Yet more are being left behind, with surging numbers of people sleeping rough and applying for hardship grants.

Figures from the Ministry of Social Development reveal the dark side of New Zealand's have-and-have-not society.

This winter, 29,000 emergency housing grants were made - doubling last year's tally - at a cost of NZ$41 million ($A38 million).

Hardship grants for food have also soared. More than half a million food grants were made in the three months to September, costing NZ$167 million ($A155 million), a figure that's tripled over five years.

The poverty crisis had a crash-through moment this winter when the desperation of those seeking hardship grants was revealed.

Advocacy group Auckland Action Against Poverty set up an open clinic in south Auckland - one of the country's most impoverished areas - where people could apply for advocates to accompany them to visit social services when they apply for the discretionary hardship grant.

The public response floored both the volunteers and New Zealand.

Struggling families - sometimes with children in tow - would line up outside the office as early as 2am in the winter mornings, just to ensure they'd see a volunteer when the office opened at 9am, who could help them secure a hardship grant.

Grants are given when families don't have enough money to eat or meet the basics.

Part of the problem is the difficulty and brutality of dealing with the government's Work and Income system, which alienates people on benefits - often some of society's most vulnerable.

"This is absolutely a crisis," AAAP coordinator Ricardo Menendez March said.

The base benefit rate for a single person without children is NZ$219 ($A202) per week.

For a two-parent family with one child, it is NZ$391 ($A361).

Calls for those rates to grow have lifted following Treasury's announcement of a NZ$7.5 billion surplus last month.

The Public Service Association has identified three priorities for that surplus: public housing, hospitals and the implementation.

"Too many New Zealanders are fighting to keep their heads above the water, and more of the status quo is not enough," Glenn Barclay, PSA national secretary said.

The government is yet to commit to raising benefit rates, despite commissioning a report that says it should.

An expert advisory group appointed by the government reported in May that it should raise benefits by up to 47 per cent.

Advocates hope that next year's election - and the government's full coffers - will provoke prime minister Jacinda Ardern to bring reform so the poorest New Zealanders won't suffer through another bleak winter.

Australian Associated Press