Almost 85,000 people formally departed Australia in the final three months of 2017 — almost 9,000 more than in the same period in 2016.
But experts are unsure about exactly what is causing the increase.
The ABS measures a resident as someone who has been in Australia for 12 out of the past 16 months, so includes many foreign students and workers on temporary visas.
Anthony Grubb, director of demography at the ABS, said these “preliminary” figures show a “significant increase” in departures of foreign students.
Approximately one-third of departures in recent years have been Australian citizens moving overseas, while almost one-half are temporary visa holders like overseas students, foreign backpackers and 457 visa workers ending their stays.