Once every three years, one year after the first sitting of parliament following the election, the latest population estimates are used to determine the entitlement of seats in the House of Representatives for each state.
In 2017, Victoria and the Australian Capital Territory each gained an extra electorate, while South Australia lost a seat, leading to a net increase of one seat from 150 to 151.
The next entitlement is due in July 2020, and the latest population figures suggest Victoria is set to gain yet another electorate (its 39th), while Western Australia is set to lose its 16th seat, and the Northern Territory would be reduced to one seat, for a total of 150.
The Parliamentary Library has published a paper outlining the timeline for the next redistribution and making rough projections about the likely population estimates. The December 2019 population figures will likely be the most recent information when the entitlement is calculated in July 2020, so they have projected population growth forward from December 2018 to December 2019.
The following table shows how many quotas each state and territory had as of December 2016 (which was used for the 2017 entitlement), in December 2018 (the most recent) and the projection for December 2019.
|State||Dec 2016||Dec 2018||Dec 2019 projection|
|New South Wales||47.32||47.28||47.24|
|Australian Capital Territory||2.54||2.49||2.51|
Victoria’s population is growing a lot faster than the rest of the country, while Queensland is growing more slowly, and every other state is falling backwards (although every jurisdiction is still experiencing a growing population).
It now looks like Victoria will gain a 39th seat, on top of the 38th they gained before the last election. Western Australia is very clearly on track to lose the 16th seat they gained before the 2016 election.
The Northern Territory is also looking set to lose its second seat. The NT also dropped below the quota in the 2002 entitlement, just after the territory received a second seat for the first time at the 2001 election, which triggered legislation in the parliament to protect the NT’s second seat. This wasn’t supported, with the parliament instead passing legislation allowing for a ‘margin of error’ where a state falls just short of the population needed for an additional seat.
The NT only just fell short in 2002 (by 295 people), whereas it looks set to fall much further short in 2020 (more like 4700), so unless the parliament was to legislate a minimum number of two MPs for each territory (in the same way that the constitution gives a minimum of five for Tasmania) it looks likely that the NT’s two seats of Solomon and Lingiari will be merged for the next federal election.
If the current projections are accurate we will see electoral redistributions in Victoria and Western Australia over 2020/21, while the Northern Territory won’t require a redistribution as it will simply merge into one electorate. No other states will fall due for redistributions in the current term, with New South Wales due after the 2022 election. Every other state, barring a change in their seat entitlement, won’t likely have a redistribution completed until after the following election due in 2025.