Continuing to work, even for just $5000 a year, after hitting 65 can substantially reduce the lump sum a person needs to live off in retirement.

Every year the Westpac Massey Fin-Ed Centre produces updated figures for how much current retirees are spending to achieve both a "no-frills" and "choices" retirement and the lump sums required to attain that.

But for the first time this year it has looked at a range of scenarios that would reduce that lump sum and make it more attainable including continuing to work part-time, working until 67 and working to 67 and saving the New Zealand Superannuation payments received in that time.

It found for a single person wanting to live a choices retirement in a major city the lump sum could be reduced from $764,000 to $670,000 if they continued work and earned a net $5000 per year after the age of 65.

Working full time until age 67 wouldn't reduce it as much, but would still bring it down to $718k and saving the NZ Super on top of that would drop it by a further $42,759.

Likewise a two-person household wanting a choices retirement in the city could drop their lump sum required from $787,000 to $693,000 if the household continued to earn $5000 a year.

Working until 67 would reduce the lump sum to $740,000 and saving the NZ Super received for a couple on top of that would drop it further to $674,000.

Claire Matthews, from Massey University business school, who undertook the research said part of the reason for looking at the different scenarios was that the lump sum figures could seem "quite daunting".

"There are some things that you can do to make them smaller without having a huge impact."

Matthews said the $5000 annual income figure showed it was a pretty minimal amount that people needed to make a big difference.

"You don't need to work a lot to make a difference."

She recognised that it was unlikely people would be able to work for their entire retirement.

"There will be some people that work until they die but for most people at some point they will reach a point where they will have to stop working altogether."

But she said research also showed that as people got to an older age they spent less and so needed less money to live off.

Matthews said alternatively people could consider working full-time until 67 and saving the money they got in NZ Super to boost their lump sum although she suggested future generations may not be able to rely on that if the age of eligibility is lifted to 67.

As well as saving more, people had the added benefit of reducing their time in retirement by the two years.

"A two year less retirement is quite reasonable for people that are fit and healthy," she added.

Already many Kiwis are working past 65. Census figures from 2013 show that more than half of men aged 65 to 69 are still working - up from 30 per cent in 2001.

Fewer women in that age group continue to work, but the proportion has increased from 15 per cent in 2001 to 35 per cent.

Figures from the latest Census are not yet available.

New Zealand Superannuation increased 2.56 per cent in the last year but still fell short of covering all of the expenses for most retirees.

The 2019 guidelines calculate a two-person household living in the city would need to have saved $787,000 to fund a "choices" lifestyle, while a couple living in the provinces would need to have saved $493,000.

The lump sums required for a "choices lifestyle" for a one-person household are $764,000 and $411,000 for metropolitan and provincial areas respectively.

Only two-person provincial households living a "no frills" lifestyle come close to being funded by New Zealand Superannuation.

A metropolitan two-person household with a "no frills" lifestyle would still require savings of $261,000 at retirement to supplement their superannuation.

Matthews said the research also assumed that the lump sum would be left in a balanced managed fund during a person's retirement.

"If you take it out and put it all in term deposits you are going to need a bigger lump sum," she said.

The average six-month term deposit interest rate has fallen to its lowest point since June 1965 this year after the Reserve Bank cut the Official Cash Rate to a record low 1 per cent.

"In the current low interest rate environment you can't afford to take all that out and put it in term deposits," Matthews said. Although some of it could be in term deposits for short term spending.

But she said it was also not a good idea to be chasing higher risk returns.

"We saw that in the finance company collapses."

Around $6 billion in people's savings was wiped by the crash with many retirees getting caught up with multiple investments spread across the sector.

While that only happened in 2008 Matthews said people had short memories and could easily dismiss it if they had not had family members directly affected by it.