Today's immigration figures are likely to indicate the start of a significant fall between now and the end of next year, Milford Asset management portfolio manager David Lewis says.
Managing the cut in migrant numbers while trying to maintain a buoyant economy meant the new Government would need to execute a ''delicate balance''.
Lewis expected the current net migration rate of about 70,000 would have been reduced to about half that number before the end of next year.
''If the process is not well managed, it has the capacity to negatively affect economic activity.''
Statistics New Zealand figures showed monthly net migration increased in October to 5580, up from 5190, but remained well below the January 2017 peak.
On an annual basis, net migration slowed to 70,410, the lowest since December 2016 but still significantly above the 20-year average of 18,500.
Craigs Investment Partners broker Chris Timms said despite a rebound last month, the migration trend had still been down. The three-month moving average had been falling since late 2016 and was now at its lowest level in more than two years.
Lewis said immigration had a large impact on economic activity.
''Roughly 60 per cent of the growth we've had in the economy had actually come from net migration.''
He acknowledged some benefits flowed from a slowdown in immigration but warned if immigration was deliberately slowed down, there was a risk of a slowing economy.
The risk sharpened when the brakes were applied at the same time as New Zealanders might be rediscovering their appetite for heading offshore in search of economic advantage, he said.