More beneficiaries are being forced into debt because they can't afford basic necessities, the Greens say.
They've released figures showing the number of beneficiaries who have borrowed money from Work and Income has increased since National came to power.
The figures show that before National won the 2008 election, 49 percent of beneficiaries had an average debt close to $2000.
It is now 60 percent - 171,000 beneficiaries - and they have an average debt of nearly $2500.
Social Development spokeswoman Jan Logie says they should be getting enough money to ensure they can afford basic necessities.
"Families who can't afford the power to heat their homes should be given grants that they don't need to repay, instead of loans that send them into spirals of debt," she said.
"More than 23,000 applications have been made for hardship assistance for electricity and gas in the year ending March 15."