That could make it the largest one in decades, if not generations.
''This will naturally speed up both aggregate demand and supply growth - something we're already beginning to detect in the local data.
Population gains alone could soon account for at least 0.4% of GDP growth per quarter.''
However, it was the demand side pressure, especially on the already stretched housing market, that would probably get the most attention from the Reserve Bank in the first instance, he said.
The economic impacts of New Zealand's booming net immigration was something to watch for in the Reserve Bank's next set of forecasts and commentary on June 12.
The suddenness of the immigration boom should not be understated, From being near-zero between 2010-12, net immigration had since doubled the rate of resident population growth to an above-average rate.
The pressure was now on, Mr Ebert said.
It was important to understand some of the details and compositions of the migrant flows, especially with many misconceptions in the public domain.
A comprehensive analysis required much time and resources but some results had been easy to get to and should be enlightening, he said.
The latest immigration boom was not so much driven by a giant wave of arrivals from Asia, all looking to buy a house in Auckland, he said.
Migrant arrivals had increased, and to a ''relatively robust level'', but it had been the plunge in migration departures that had mostly driven the net gains.
There were 64,445 migrant departures in the year to April, compared to 82,441 in the previous corresponding period.
Arrivals increased 11,594 in the same period.
The tilt was more pronounced when tracking the migrant flows of only New Zealand citizens, Mr Ebert said.
Departures for the group fell 16,716 between the year to April 2014 and the year to April 2013 to 64,445. Arrivals increased 3234.
The fall in departures explained 84% of the change in net immigration among New Zealand citizens in the past year or so.
New Zealand citizens returning from aboard, including from Australia, were a relatively minor driver.
''The message that drops out of this is it is extremely difficult for policy officials to target a net amount of inward migration when the departure side is free to move - coupled with the fact Australians and New Zealanders wanting to move to New Zealand are free to do so and are not subject to the restrictions folk from other countries are,'' Mr Ebert said.
