The net flow of people coming to live in New Zealand will peak next month at nearly five times the long-term average - adding more fuel to the Auckland housing market.
Migration levels are not expected to return to normal until 2017.
Net migration inflows have recently been driven by fewer New Zealanders leaving for greener pastures overseas, but that has changed.
Increased arrivals are now the larger factor and accounted for about two-thirds of the increase in the past year.
Annual net inflows - the total number of immigrants less the annual number of emigrants, including both citizens and non-citizens - are now expected to peak at around 57,000 in the year to June, before returning to the long-run average net inflow of 12,000 by 2017.