In the second half of Good Returns TV's KiwiSaver election special, Kernel's Dean Anderson and Pie Funds' Ana-Marie Lockyer turned to a question the major parties have largely avoided: the link between KiwiSaver and NZ Super.

Kernel chief executive Dean Anderson says the KiwiSaver withdrawal age should be lowered to 60, in line with Australia's settings, using earlier access as "the carrot" to justify lifting the NZ Super age to 67 or 68.

Speaking on Good Returns TV, Anderson said raising the Super age by even a year would save close to a third of a percentage point of GDP, adding up to around 8% of GDP over 30 years.

He argued the current settings get the trade-off backwards: locking up KiwiSaver until 65 while leaving NZ Super's age untouched ignores the fiscal pressure of an ageing population.

Pie Funds chief executive Ana-Marie Lockyer disagreed, warning that lowering the KiwiSaver age could send the wrong signal about when people should stop working altogether, pointing to research showing half of New Zealanders aged 65 to 75 are still earning an income.

Both executives criticised the two major parties for campaigning on KiwiSaver policy while avoiding NZ Super, despite the schemes being legislatively linked.

The pair also responded to ACT's proposal to exempt KiwiSaver earnings from tax, effectively cutting the Prescribed Investor Rate from 28% toward zero. Lockyer backed the principle — "the power of compounding is really, really important," she said — but noted the benefit would skew toward middle- and higher-income earners who already pay lower PIR rates.

She proposed a cheaper alternative: making the first $5,000 of annual contributions tax-exempt, directing more benefit toward lower earners and the self-employed.

Anderson backed the goal but questioned the cost, warning that if the policy "blows out to billions of dollars," it needs weighing against the cost to the country overall.

Both identified the self-employed and small business owners as KiwiSaver's biggest coverage gap, with no party offering policy to close it.

Anderson pointed to New Zealand's large base of small business owners and the growing gig economy as reasons the gap will widen.

Lockyer said KiwiSaver is an underused diversification tool for business owners, who often "overthink the value of their business," and proposed making contributions tax-deductible through the business to build the savings habit.

Anderson and Lockyer said the apparent cross-party convergence on raising contribution rates was encouraging, and called on politicians to agree a long-term, bipartisan settings framework rather than treating KiwiSaver as a three-year political football.

Part one of the debate, covering compulsion, contribution rates and the baby bonus, is available on Good Returns TV, along with the full part two conversation.

Catch up on part one of the debate, covering compulsion, contribution rates and the baby bonus, and watch the full part two conversation with Dean Anderson and Ana-Marie Lockyer on Good Returns TV.