Keeping New Zealand Superannuation in its current form may mean more money is transferred from the working poor to the rich in the future, a researcher is warning.
Jenesa Jeram, a research fellow at think-tank the New Zealand Initiative, said the biggest surprise in undertaking research on New Zealand's superannuation system was that it was affordable.
"The report has been a bit of a surprise. I went into it believing New Zealand Superannuation was not going to be affordable in the future."
But she said just because New Zealand could afford it did not mean it was the best use of public money and warned that continuing to fund superannuation at the current rate may be at the expense of more needy groups.
"Our tax and welfare system is generally progressive: money is transferred from the rich to the poor.
"This could be reversed as the population ages and fewer people work, so that more money is transferred from the working poor to the relatively rich."
"The public should be aware that maintaining the pension age comes at an increasing cost, when that money could go towards people in real hardship."
Jeram said already the working poor were suffering at the expense of the wealthy.
"It is already happening."
She pointed to hardship rates for the elderly which were 3 per cent compared to 11 per cent for the population as a whole and 18 per cent for households with children.
The current Labour coalition Government has ambitious plans to target improving child poverty.
Jeram said while that may be possible at the moment in the future it may not be so easy in the future.
And she urged politicians to make changes now before ageing voter demographics made it harder to convince the public to make changes to New Zealand Super.
Jeram said the age of eligibility should be linked to health expectancy - a measure for how long people live for without any major health complications.
She said health expectancy rather than life expectancy was a good measure to use because it indicated what age a person may be able to work until.
The health expectancy is currently 71.8 years for New Zealand women and just under 70 years for men.
Some have suggested having a different retirement age for men and women and for different ethnicities to match their health expectancy would make superannuation fairer.
But Jeram said it should be the same for everyone to fit with the universal system New Zealand has.
She said linking the pension to health expectancy would also give flexibility for future adjustments rather than a one off rise with a long lead in which was likely to be out of step with labour force trends by the time it comes into force.
Jeram said super should also be indexed to inflation growth rather than wages and inflation.
"Decoupling NZS from rises in wages is way of ensuring productivity gains reduce the costs of NZS.
"The real purchasing power of NZS should remain the same while the real purchasing power of wages would increase."
Jeram said contributions to the New Zealand Superannuation Fund should not come at the expense of paying down debt.
"The Super Fund should not be relied on to reduce the future costs of NZS (it cannot do that)."
Jeram also urged the Government to focus on increasing productivity as that would make New Zealand Super and everything else more affordable.
But she said any changes needed to be signalled well in advance to give people time to prepare.
"Consecutive governments do taxpayers no favours by refusing to tweak Super.
"Governments could be spending taxpayers' money more efficiently, and the public needs warning of proposed changes to make other arrangements."