Auckland mayoral hopeful John Tamihere wants landlords to promise not to increase rents, in exchange for a freeze on rates.

The controversial contender on Monday said he wouldn't raise rates in his first term, if elected in October.

"As a part of a general rates freeze over the next three years, I will ask landlords in Auckland to show goodwill by freezing rents for the next three years also," the former Labour Party MP said.

"Like all Aucklanders, landlords will not be paying increased rates, there are currently unprecedented low interest rates, and a capital gains tax is off the table. There has never been a better time for landlords to show their support for a rents freeze.

"My call to all landlords is a collective call to action that we all need a three-year breathing space to fix a number of broken things, so we can future-proof our city... I'm sure landlords will reflect deeply on their conscience because at least one leader has the backbone to ask them to step up."

But Mayor Phil Goff says rather than giving the city a breather to fix things, it'll suck the council's coffers dry, calling the idea "incoherent and lacking in basic financial understanding".

"Tamihere has already promised a rise in water rates of $200-$300 for every household, which equals to a 12 percent increase in average general rates. So, to suggest a 3.5 percent rates cut is to take much more with one hand and give a little bit with the other," the incumbent - also a former Labour MP - said.

Goff has proposed a maximum 3.5 percent-a-year rates increase, up from the 2.5 percent increases he delivered in his first term.

"Under [Tamihere's] plan, the city would lose out on $3.8 billion dollars' worth of rates revenue on top of the $4.3 billion lost from the regional fuel tax. Where is the money going to come from to pay for the work that we desperately need to do in Auckland like transport and housing infrastructure?"