People getting an unemployment benefit for more than 12 months would have to be reassessed under a National government.
Leader John Key, outlining the party's benefits policy in a speech at the Papakura Returned Servicemen's Association on Monday, said 30% of the 17,710 people receiving an unemployment benefit had been out of work for more than a year. They would have to reapply for their benefit within 12 months of National taking office.
Mr Key also announced that people on the domestic purposes benefit would have to spend at least 15 hours working, training or job-seeking once their youngest child turned six.
That would also apply to 5600 sickness and invalid beneficiaries categorised as capable of working.
National believes it is in the interests of sole-parent families to be in the workforce, and argues that work obligations have been successful in reducing the number of people on the unemployment benefit.
The party would also increase the amount beneficiaries could earn before their benefit was reduced, from $80 a week to $100 dollars a week.
But Social Development and Employment Minister Ruth Dyson says children would suffer when their parents' benefits were reduced. The changes would also lead to a huge increase in bureaucracy, she predicts.
United Future leader Peter Dunne says while aspects of National's benefits plan look good on paper, the policy risks being overly punitive and harsh in practice.
Child Poverty Action Group chief research analyst Donna Wynd is questioning the policy on the domestic purposes benefit.
Ms Wynd says it would affect about 38,000 of the 96,000 single parents on the benefit, which she says seems like a lot of policy work for a small number of people.
She says sole parent families have double the rate of disabled children compared with the general population, and it would also be hard to find work with suitable hours.
National is promising to index benefits to inflation, enshrining in legislation Consumer Price Index adjustments to welfare. It is currently done by convention.
Under National, beneficiaries who needed frequent benefit advances would be required to obtain budgeting advice, and those who do not take up budgeting services would not be eligible for any further advances.
Mr Key says benefit advances are given with apparent ease, and beneficiaries are finding themselves in increasing debt.
However, a budget advisory service says agencies must get more funding if National's policy is to have any chance of success.
Darryl Evans, chief executive of Mangere budgeting and family support services, says services are struggling to provide help on current funding.
Demand for such services is already at an all-time high and more money must be provided to enable staff to keep up with the extra workload that would eventuate, he says.