Migration Program planning levels are only one factor in how many people migrate to Australia each year. The Australian Bureau of Statistics measures net overseas migration (NOM). NOM is the difference between people arriving in Australia and people departing from Australia. Migrant arrivals to Australia are counted in NOM if they are in Australia for a total of 12 months or more during a 16-month period. Therefore, this counts people who arrive on a permanent visa, but also those who arrive on a temporary visa and stay for a year or more, for example to study or work.