New Housing Minister Phil Twyford says it would be unwise for Auckland home owners to assume they've hit the jackpot when new valuations are revealed tomorrow, and take on extra mortgage debt.
Provisional data shows housing values in Auckland shot up 45 per cent since the last valuation three years ago.
Owners will find out what their home is valued at 9am tomorrow when Auckland Council posts the information on its website. Interest was so high in the last valuations that the website crashed.
But Twyford says people shouldn't go overboard if their valuation has increased.
"I think they would be unwise to get the new ratings and assume that's the market value right now and go out and buy whatever it was they wanted to buy like a new car," he said.
"I do think people lose their heads a bit. You can see in the past few years there's been a massive increase in household debt as people have seen their houses rise in value and they've borrowed against that. Most of that is mortgage debt.
"The problem that we have is we've come to see housing as an investment asset and not as a roof over our heads, or a home to raise a family in. When that becomes your mindset housing becomes just another commodity."
The consequence of rising valuations was increased homelessness and low rates of home ownership, he said.
While the revaluation figures will be taken into account when new rates are set, officials are reminding the public that a rise in their rates will not happen overnight.
Council head of rates Debbie Acott said it would not be till next year that the true impact of the revaluation on rates would be evident.
"We won't know...until we agree our next budget in 2018, so I encourage Aucklanders to view these valuations with that in mind."
She also said just because you had a high increase in property value did not mean there would be a corresponding increase in rates.
The rise in rates was more to do with how much the value of a property rose in comparison to others.
Acott said there was also support for those who struggled to pay their rates.
"If someone wants to pay more frequent payments...we also have rates rebates for people on a low income and the ability to postpone rates and that's not means tested."
According to the council website the income threshold for eligibility is $24,790 a year, but you could still be eligible for a rebate depending on your rates bill and the number of dependants you have.
Late penalties can also be removed under certain circumstances, including if you notify council you will be late due to insufficient funds and pay within 14 days of the penalty date - though this can only happen once within two years.
Council valuations are released triennially after a region-wide revaluation of all commercial, industrial and rural properties. Every council in New Zealand is legally required to do them.
The RV for each property is set by council and used for the purpose of determining the proportion of rates each property owner has to pay. Because it is based on the capital value (CV), the RV is the same as the CV.
Auckland chamber of commerce CEO Michael Barnett has called on councils to look at cutting this link between property valuations and rates.
"Rates pay for services delivered by councils. If the level and cost of services provided don't change, then it is wrong and unfair for a council to impose rate increases just because the value of the property has increased."
Auckland Ratepayers Alliance spokeswoman Jo Holmes said the reality was that rates and valuation figures were linked.
"That's what we have to live with, I am just hoping it's not an excuse to put up rates much higher than was promised."
Mayor Phil Goff had during his mayoral campaign pledged to keep rates increases to 2.5 per cent or less this term, but has indicated this could be in jeopardy.
While he had achieved 2.5 per cent in his first budget this year, the council was right up against its debt ceiling, putting huge financial constraints on the mayor heading into a new 10-year budget.
Mortgage broker Bruce Patten any rise in rates would hit those who could least afford it first - first-home buyers and retired people - as the more affordable areas were where growth significantly above the average was located.
Council's reveal of the property revaluation trends last Thursday showed the more "affordable" suburbs had been the ones hit by the highest increase in rates - well beyond the average 45 per cent across the whole city.
There were two that rose in value by more than 100 per cent since the last council valuations in 2014 - Paerata-Runciman and Wainui/Waitoki, which grew by 102 per cent.