New Zealand's migration has hit record levels, as Kiwis flock overseas.

The year to September had a historic net loss of 44,700 citizens.

Overall annual net migration was at a record near 119,000 for the same period.

Demographer Paul Spoonley says they're extraordinary figures, unlike anything seen before.

"Last year, the Productivity Commission did a fantastic report, which looked at migration. One of the things they said is- we've got an infrastructure deficit. I thought we might have a bit of a pause, but no."

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