The nation's biggest bank unveiled the decision this morning. Effective immediately, residential investors will not be able to borrow more than 60% loan to value.
It comes as the Reserve Bank moves to reinstate LVR limits that restrict lending above 70%.
ANZ's move goes one step further, and marks a significant clampdown on landlords and investors following a record surge in the housing market.
There are no other changes for ANZ mortgage customers, including owner-occupiers and first home buyers.
In an email to advisers, ANZ's head of mortgage adviser distribution Baden Martin said: "Over the last two months we’ve seen record mortgage lending. A fifth of this has gone to first home buyers and about a third has gone to residential property investors. If that trend continues we’re concerned that the current settings could lock many first home buyers out of home ownership."
"As New Zealand’s largest lender, requiring a 40% deposit from residential property investors is a step we can take right now to help bring balance to the housing market. It’s in everyone’s interests for residential property prices to be sustainable long term."
In an extraordinary move, ANZ managing director of personal banking Ben Kelleher said he would recommend to the Reserve Bank that LVRs be set at 60% for investors.
The developments mark a major change in the lending market, with banks under pressure to keep a lid on investor lending amid a rise in high LVR investor lending and investor activity.
Kelleher said the bank made the decision as current conditions "favour property investors", "potentially locking a generation of New Zealanders out of homeownership".
He said the bank had monitored the impact of low rates, reduced LVRs and "existing issues with supply and demand".
Kelleher added: "It’s in everyone’s interests for residential property prices to be sustainable long-term, and for homeownership to be accessible to as many people as possible.
"As New Zealand’s largest home lender, decreasing the LVR on residential investor lending is one thing we can do to help bring balance to the residential property market," he added.