The Reserve Bank claims its crackdown on property investors will slow Auckland house price growth by 2 to 4 percentage points during the first year of the new regime.

On Wednesday the central bank published a consultation paper exploring the issues and impacts of its new rules.

The beefed-up restrictions, which come into force in October, will require investors in Auckland to hold a 30 per cent deposit.

They are one of several measures aimed at taking some heat out of the market, with the regulator concerned about the possibility of a crash.

The Reserve Bank estimated the tighter restrictions would knock 2 to 4 percentage points off Auckland house price growth over the first 12 months.

Outside Auckland, where the existing rules around minimum deposits will be relaxed, the bank expected the changes to increase house price inflation by about 1 percentage point and sales by 4 per cent.

Investors borrowing with less than a 30 per cent deposit accounted for about 13 per cent of transactions in the Auckland market, according to the Reserve Bank's figures.

However, it said "policy leakage" meant the new rules would only dampen sales volumes by around 7 per cent.

The bank estimated around a quarter of investors would be able to restructure their finances in order to meet the higher deposit requirements.

It also expected cashed-up investors to step up their activity in the market, which would further offset the impact.

In order to allow for occasional mistakes by lenders or special circumstances, the bank has proposed a 2 per cent speed limit for the new rules, rather than an outright ban as first announced.

Submissions on the rules close on July 13.

Property investors have already voiced their opposition to the new regime, saying it will push up rents and fails to address underlying issues.

The Reserve Bank acknowledged there could be fewer people in each dwelling if there was a shift from rental property to owner-occupied properties.

"However, any effect on occupancy is not expected to be large," it said.

Last Friday, the bank also released its final policy decision on what exactly constitutes a property investor, for the purposes of the new rules.

It defined the new class in the broadest way possible as any property which is not owner-occupied, which will include baches and holiday homes in most circumstances.

It also forged ahead with plans to force banks to hold more capital against investor loans, a move which bank bosses say will push up interest rates.