On Thursday, Finance Minister Grant Robertson released the first budget of Labour's second term - and the first of Jacinda Ardern's parliamentary majority.

The centrepiece is a boost to social security, with baseline benefits increased immediately by $NZ20 ($A18.60) a week in a $NZ3.6 billion ($A3.3 billion) four-year splash.

Opposition leader Judith Collins said the lack of tax cuts or incentives showed Labour was about "welfare first and work second".

"All New Zealanders are feeling the pinch right now - not just those on jobseeker benefits and the minimum wage - so where is the plan to take the entire country back to prosperity?" she asked.

However, Ms Collins said she supported the benefits increase as "we have to at the moment because the cost of living has gone up so much".

Right-wing party ACT took aim at Treasury's projections, labelling it a "La La budget because the government is in La La Land".

"The budget assumes that unemployment will be 4.4 per cent and economic growth will be 4.4 per cent by 2023," leader David Seymour said.

"They are in La La Land. How can that possibly be the case with the Government's anti-growth, anti-business agenda? We're heading straight for an iceberg with Grant Robertson at the helm of the ship."

Banks were more optimistic.

ASB senior economist Mark Smith said the budget "made all the right noises", though "a long journey lies ahead".

"Wisely, the government have not chosen to go down the austerity route and aim to return the books to surplus as quickly as possible," he said.

"To date there has been little progress in boosting economy wide productivity, addressing bottlenecks in transport and improving housing affordability."

The NZX 50 Index was largely unchanged after the budget, at 12,380 points, while the NZ dollar was also steady, buying 93 Australian cents.

Australian Associated Press