However, Finance Minister Grant Robertson isn't so sure after unveiling his fifth budget on Thursday to a mostly negative reaction on both the left and the right.

The budget contains huge government spending, underwritten by enhanced tax revenues from record low unemployment, funding major health and climate change reforms.

There's also a $NZ350 ($A318) handout to more than two million Kiwis struggling under record inflation, and a smattering of offers to the least well off, including cut-price public transport.

The inflation relief has stolen local headlines, much to the finance minister's annoyance.

"Despite what the media have told you, there actually was something other than the cost of living package in the budget," he told a packed post-budget business lunch in Wellington.

Mr Robertson presents the budget as a key moment to land big reforms, including the country's first emissions reduction plan and a massive health shake-up and investment.

The opposition has derided the budget as a missed opportunity for tax reform that could avoid net migration loss.

New Zealand has long suffered a brain drain to Australia, given the superior wages and conditions on offer in many industries.

However, over the last decade New Zealand has overcome the westwards Tasman drift with immigrants from elsewhere, producing a positive migration tally.

That has now come to a halt, with Stats NZ last week confirming an overall net migration loss of 7300 people in the 12 months to March.

Despite soaring inflation, which at 6.9 per cent outstrips wage growth, and rising interest rates, Treasury has forecast a net migration gain of 14,000 this year, rising to 40,000 in 2026.

That's contrary to the current pattern, and predictions from elsewhere in government of a mass movement of between 50,000 to 125,000 Kiwis overseas due to the border reopening.

Any big shift would cause huge stress in a tight labour market, with just 3.0 per cent unemployment.

Mr Robertson didn't say which migration predictions he believed.

"It's difficult for everybody to assess at the moment," he said, "but New Zealand remains an attractive place for people to come to."

The budget also contained funding for two of the Labour stalwart's pet projects: fair pay agreements which allow for industry-wide collective bargaining, and an income insurance scheme to give relief to redundant workers.

To many groups working with low-income Kiwis, it wasn't enough.

"We were hoping for something brave," Child Poverty Action Group spokeswoman Innes Asher said, with The Salvation Army, Save The Children and the "Fairer Future" anti-poverty coalition agreeing with that sentiment.

The budget also displeased the universities sector, with staff, students and research groups all condemning a cut in real terms to funding.

Australian Associated Press