The third outlier was after COVID, when borders re-opened and there was a population surge. This ushered in the highest rate of population growth since the 1960s boom – which was driven by the birth of Baby Boomers as well as a rise in immigration. In real numbers, at the post-COVID peak, the population grew by 663,000 people in 12 months.

So when commentators say there has been unprecedented migration in recent years, that is supported by the data showing a migrant boom after Australia reopened its borders. However, that claim does not factor in the unprecedented dip in migration that immediately preceded it, in 2020 and 2021.

How significant is migration to Australia’s population growth?

There are two elements to population growth: natural increase (births and deaths) and immigration.

Natural increase is the number of people born minus those who die.

The natural increase in Australia’s population hovered between 100,000 and 200,000 per year over the past two decades. But since 2022, it has tended towards the lower end of that spectrum. That’s because birth rates are dipping and more people are dying. The decline in Australia’s birth rate means natural increase plays a diminishing role in overall population growth.

Migration has been the main source of Australia’s population growth for the past 20 years.

One exception was during the pandemic, when there was negative net overseas migration due to border closures. Before that, the last time that births surpassed immigration as the leading source of population growth was in 2004.

Diving into the migration numbers

The figure that tells us how much migration contributes to population growth is called “net overseas migration”. You might also hear this being referred to as “the NOM”, which is calculated by the Australian Bureau of Statistics.

NOM is a measure of how many people arrived in Australia in a given period, minus how many people departed. To be counted in the NOM, a person must have spent 12 months of the previous 16 months in Australia. That’s to separate out tourists or people coming for short-term stays. The NOM counts foreign-born migrants, including people on temporary visas, as well as Australians who move overseas or return from abroad.

The federal government also estimates what the NOM will be in its annual budget. Its projections run four years into the future. NOM is influenced by factors the federal government controls, such as immigration policy. It is also influenced by factors it does not control, such as when Australians living abroad choose to come home.

Federal budget estimates have been consistently off the mark since 2019 because of the uncertainties brought on by the pandemic.

As shown in the chart above, in 2019-20, the Morrison government expected the next year’s NOM to be 271,300. Instead, when the pandemic struck and borders shut, it ended up being -85,000.

Adjusting to the new normal, the Morrison government, in its March 2021 budget, forecast the 2021-22 NOM would be -77,400. But by the time the end of June 2022 rolled around, borders had reopened, and NOM was in reality 207,900.

The Albanese government ran into similar troubles. In October 2022, it forecast NOM for the 2022-23 financial year would be 235,000. Instead, there was a migrant boom, and NOM hit a record 538,300.

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These figures became a regular feature of political debate. The Albanese government came under sustained pressure last term as its NOM forecasts repeatedly blew out, with a higher than expected number of people arriving in the country, and a lower than expected number of people leaving it.

Population figures on par with long-term projections

A wider view of the budget forecasts can help put these numbers in perspective.

The anti-immigration protest movement frequently cites statistics showing 1 million people moved into the country in two years – facts which are verified in ABS figures above.

But the other key claim of protesters – that the government has ushered in a huge group of migrants by stealth – is not. Again, that’s because of the pandemic.

Population forecasts moved around a lot during the pandemic. But if you return to the former Morrison government’s forecasts from 2019-20, and apply that rate of growth into the future, the population in 2024 (27.4 million) is lower than what had been anticipated (27.9 million).

A note on the data

The population and NOM figures referenced here come from the Australian Bureau of Statistics. They are the most reliable indication of population change.

Last month, the bureau put out a statement warning against using its other data sets, such as “overseas arrivals and departures” figures, to deduce population change.

“This data does not reflect the official ABS definition of migration and may lead to inaccurate conclusions on migration. Overseas Arrivals and Departures (OAD) data is a count of border crossings rather than migration,” it said.

“For example, this means a person who has been living in Australia for three years on a temporary visa, and travels overseas multiple times, can count as a long-term visitor arrival many times, even though they only migrated here once.”

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