Labour says families are spending much more of their income on housing than when John Key became Prime Minister.
Using data from Statistics New Zealand, Labour says the average household now spends $16,533 a year on mortgage payments and rent - up from $11967 in 2008, an increase of 38 percent.
In Auckland, the increase is even bigger - from $15,372 to $22,649, up 47 percent.
"These costs don't get picked up in the Consumer Price Index (CPI)," leader Andrew Little told Paul Henry on Thursday.
"When the Government says the CPI is less than 1 percent and average wage growth is just over 1 percent, hey-ho everybody's happy. But CPI doesn't pick up the rising cost of running a mortgage, or paying your rent, and that's what these figures are about.
"There are real living costs that people are having to pick up and that aren't picked up in the official statistics, and show that life is getting harder."
The CPI is a measure of inflation using common purchases, including food, alcohol and cigarettes, clothing, household maintenance, transport and health.
And it does in fact include rent - Mr Little's office told Newshub he "misspoke", but the point remains that household costs are rising much faster than inflation.
"I've met young couples with $800,000 mortgages. That beggars belief," says Mr Little. "One in five wage and salary earners are now spending more than half of their take-home pay on paying the rent or mortgage."
Housing Minister Nick Smith has been contacted for a response.
Mr Little believes housing is the Government's weakest policy link, particularly in Auckland. He ascribes much of Labour's success in the Mt Roskill by-election to rising rents and mortgages.
"In the time I spent there, unprompted, pretty much 90 percent of the people I spoke to, housing came up as the big issue for them. If it wasn't the rent, it was the overcrowding," he told Paul Henry.
"I met this real estate agent, been in the business 25 years, and he said his biggest worry is that his kids will never ever be able to afford their own home. He knows a thing or two. He's comfortable, but he can't afford to fund them into a house.
"That is a big story in Auckland, and I have to say, National has just never got it."
House prices in Auckland do appear to be levelling off, though it depends on how they're measured. The Real Estate Institute of New Zealand recorded a 4 percent annual drop in November, while Trade Me's reporting a 13 percent rise.