Labour's housing spokesman Phil Twyford said the findings were New Zealand's "badge of shame".
During question time in Parliament yesterday, he also cited the latest AMP 360 Housing Affordability Index, which shows that housing has become less affordable for Auckland's first-home buyers under National.
The average first-home-buying couple in the city are spending 47.9 per cent of their income on their mortgage - up from 38.9 per cent in 2008.
"It now takes nearly half the income of a typical first-home buyer to buy a lower-end home in Auckland," Mr Twyford said.
Housing Minister Nick Smith defended the Government's record on housing, saying that overall, properties were still more affordable on a mortgage-to-income basis than in 2008.
The AMP 360 index shows that the average individual is spending 86.9 per cent of their income on their mortgage in Auckland - down from a peak of 101.7 per cent in late 2007, when Labour was in power.
That trend is similar nationwide, where the income-to-mortgage ratio has fallen from 73 per cent in September 2008 to 54 per cent in February.
Dr Smith said efforts to increase housing supply and record-low interest rates were helping New Zealanders get into homes.
Average interests rates were twice as high under Labour, he said.