Electoral redistributions expected during the 47th Parliament

Updated 14 November 2022

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Christopher Giuliano
Stats and Mapping

Executive summary

This is the second issue of this paper and replaces the version published on 25 August 2022. Tables, charts, and text have been updated as per the latest quarterly release of ABS population data. The Parliamentary Library will re-issue this paper after each of the next 3 quarters (the 3rd being the data that will be used for the determination).

The periodic redrawing of federal electoral boundaries is required by law to maintain electoral divisions (also known as electorates or seats) of roughly equal enrolment size within a state or territory. Redrawing of boundaries is known as a redistribution.

Redistributions take place every 7 years or can be brought about by the ‘representation entitlement trigger’, which determines the number of members of the House of Representatives a state or territory is entitled to, based on its share of the population.[1]

During the life of the 47th Parliament, redistributions are expected to occur in Western Australia, Victoria, New South Wales, and the Northern Territory.

Population projections based on the 2021 Australian Bureau of Statistics Census of Population and Housing (the Census) suggest that Western Australia may gain a seat and New South Wales and Victoria will both lose one.

There’s a remote chance that Queensland gains a seat, but since this is neither ‘expected’ nor ‘likely’ this outcome has not been included when either of these terms are used in this paper.

The scheduled 7-year redistribution for the Northern Territory should go ahead during the 47th Parliament, but scheduled redistributions for Queensland, Tasmania, Australian Capital Territory and South Australia will be deferred until the next parliament, as they fall too late in the parliamentary term. No changes in seat numbers are expected to occur in these states and territories.

Based on the most likely entitlement outcomes, there should be one less seat at the next election—150 rather than 151 seats, the same number as there were from 2001 to 2016.

Caveats

The net corrections to jurisdictions’ populations based on the Census have been the largest since at least 1991 and will cause changes in entitlement to Western Australia and Victoria, and quite likely to New South Wales.[2] These corrections have been associated with the impact of COVID-19, driven by factors such as people updating their home addresses with Medicare when they get vaccinated for COVID-19[3] and actual interstate migration. Similarly, Net Overseas Migration (NOM) has fallen to its lowest in a century, meaning fewer migrants moving to Sydney and Melbourne areas, decreasing those states’ population share.[4] Whether these COVID-19 associated changes will continue, stop or reverse between March 2022 and December 2022 cannot be known, and any such changes will affect projections shown here.

This paper uses a simple annual projection based on the most recent Australian Bureau of Statistics (ABS) Estimated Resident Population (ERP). If the population revealed by the December 2022 figures (to be released in June 2023) differs significantly from these projections, the results may change.

 

Contents

Executive summary
Caveats
Introduction
Redistribution provisions

Representation entitlement
Expiration of 7 years
Deferral of redistribution
Past and projected changes in states’ share
Western Australia
Victoria
New South Wales
Queensland
South Australia
Tasmania
Special cases—the Territories
Australian Capital Territory. 9
Northern Territory. 10
Conclusion

 

Introduction

Each state and territory is divided into federal electoral divisions (or seats), each with a member in the House of Representatives. The number of divisions is based on population and requirements set out in the Australian Constitution.[5] These requirements stipulate that the boundaries of divisions are to be redrawn or redistributed from time to time to allow for changes in the share of population between states and territories, and to ensure equal representation between divisions within each state and territory.

This paper looks at which states or territories may have their electoral divisions redistributed during the course of this Parliament. Redistributions determined during the 47th Parliament will come into effect at the next election.[6] The actual redistribution process (or the redrawing of boundaries) is not covered in this paper.[7]

Four redistributions are expected to occur prior to the deemed expiration of the 47th Parliament.[8] This paper outlines the reasons why.

Redistribution provisions

Section 59 of the Commonwealth Electoral Act 1918 (the Electoral Act) sets out the 3 provisions that trigger electoral redistributions.[9] Briefly, these are:

  • Representation entitlement—a redistribution must be held if the number of members of the House of Representatives to which a state or territory is entitled changes.
  • Malapportioned divisions—a redistribution must be held if the number of electors in more than one third of the divisions in a state, or one division in a territory, deviates from the average enrolment in that state or territory by greater than one-tenth more or one-tenth less for a period of more than 2 months (this provision has not been a trigger for a redistribution since it was introduced in 1984 and is unlikely to be a trigger during this Parliament, and is therefore not discussed here).
  • Expiration of 7 years—if neither of the above provisions triggers a redistribution in a state or territory within 7 years of the previous redistribution, then a redistribution must be held in that state or territory.

Representation entitlement

Under section 46 of the Electoral Act, the Electoral Commissioner ascertains the populations of the states and territories using data obtained from the Australian Statistician, as at the day after the anniversary of the first meeting of a newly elected House of Representatives, provided that the ‘House of Representatives has continued for a period of 12 months’. Section 48 of the Electoral Act specifies the way representation entitlements are calculated from these population numbers.[10]

The first meeting of the House of Representatives took place on 26 July 2022, so on 27 July 2023 the Electoral Commissioner will ascertain the various populations after obtaining the latest population numbers published by the ABS. According to the ABS, the most recently published population numbers that will be available as at 27 July 2023 will be released on 15 June 2023 and will relate to the end of December 2022.[11]

It is important to note that entitlement to members of the House of Representatives is based on each jurisdiction’s share of the population. Just because a state’s population is increasing does not necessarily mean its entitlement is increasing. For example, although New South Wales’ population has continued to grow, its share has declined as its growth has not been as fast as other states. In this publication, therefore, comparative words such as ‘increase’, ‘decrease’, and ‘stable’ refer to the jurisdiction’s share (entitlement), not its population.

One way to simulate the July 2023 entitlement determination is to take the latest ABS population data and project them to December 2022 using the growth from March 2021 to March 2022 (one year of linear growth) over three quarters (March 2022 to December 2022). Table 1 shows the population projections and estimated representation entitlements of the states and territories using this method. Separate discussion for each state follows.

Table 1: Estimated representation entitlements

Population projections Dec 2022 Calculated number of members (a) Entitlement Change (b)
New South Wales 8 163 602 46.368 46 -1
Victoria 6 624 614 37.627 38 -1
Queensland 5 365 470 30.475 30 0
South Australia 1 827 104 10.378 10   0
Western Australia 2 797 683 15.890 16 +1
Tasmania (c)  574 238 3.262 5   0
   Total 6 states 25 352 711 145   -1
Northern Territory  251 120 1.426
Cocos (Keeling) Islands   620 0.004
Christmas Island  1 751 0.010
   Total NT (d) 253 491 1.440 2   0
Australian Capital Territory  458 416 2.603
Jervis Bay   303 0.002
Norfolk Island  2 271 0.013    
   Total ACT (d) 460 990 2.618 3   0
Australia 26 067 192 150   -1

Note: For representation entitlement purposes, s48 of the Electoral Act states that Jervis Bay and Norfolk Island are included with the Australian Capital Territory and the Northern Territory includes the Cocos (Keeling) Islands and Christmas Island. Norfolk Island, the Cocos (Keeling) Islands or Christmas Island will not be included if they are determined to be entitled to a member of their own.
(a) Derived by dividing the population of a state or territory by a population quota, that is, the population of the 6 states divided by twice the number of senators for the 6 states (144) because section 24 of the Constitution requires there to be ‘as nearly as practicable’ twice as many members as senators. The population quota calculated here is 174,858. Section 45 of the Electoral Act interprets ‘People of the Commonwealth’ as not including any Territory.
(b) Change over current entitlement.
(c) Tasmania is one of the original (6) states at the establishment of the Commonwealth of Australia. Section 24 of the Constitution entitles each original state to at least 5 members.
(d) For the Northern Territory and the Australian Capital Territory, if their calculated number of members is between 1.3333 and 1.5 then they are allocated 2 members. If it is between 2.4 and 2.5 they will be allocated 3 members. Normal rounding occurs from 2.5 upwards. This is based on a harmonic mean as calculated in subsection 48(2AA) of the Electoral Act.

The projections and calculations above indicate that the current representation entitlements could change in Western Australia (+1), New South Wales (-1), and Victoria (-1). Because the calculated number of members is rounded to the nearest integer, the closer a remainder is to 0.5 the less likely entitlements in Table 1 may eventuate. For example, Queensland’s estimated quota of 30.475 is only 0.025 away from being rounded up to 31 instead of being rounded down to 30, whereas Western Australia’s 15.890 could move by almost an entire half-quota up or down and still be rounded to 16 seats.

Expiration of 7 years

Section 59 of the Electoral Act sets out that a redistribution in a state or territory must commence within 30 days of the expiration of 7 years after the most recent redistribution in that state or territory. Table 2 (at the end of this article) sets out the date of the most recent electoral redistribution held in each state and territory.

Redistributions for New South Wales, the Northern Territory, Tasmania, Queensland, the Australian Capital Territory and South Australia were scheduled to occur during this Parliament, under this provision. However, only the Northern Territory looks to keep to that schedule as the New South Wales redistribution is likely to be deferred until after the determination of entitlement and the other jurisdictions’ redistributions are likely to be deferred due to being late in the parliamentary term.

Deferral of redistribution

Under subsections 59(5) and (9A) of the Electoral Act, a redistribution may be deferred if:

  • it is triggered by the expiration of 7 years since the most recent redistribution was determined, and
  • the direction for the redistribution to commence is due is scheduled to be made by the Electoral Commission within the 13 months after the first sitting day of a House of Representatives, and
  • the determination of the number of members of the House of Representatives has not yet been made, and
  • the Electoral Commission is of the opinion that when the next determination of members is made, there will or may be a change in the number of members the state or territory is entitled to.

Only New South Wales is scheduled for a redistribution in the first 13 months of this Parliament. Its entitlement is expected to change, so its deferral is likely.

Under subsections 59(4) and (9) of the Electoral Act, a redistribution triggered by the expiration of 7 years and scheduled to commence within 12 months before the expiration of a House of Representatives is deferred, and will instead commence within 30 days after the first meeting of the new House of Representatives.

This should apply to Tasmania, Queensland, Australian Capital Territory and South Australia, which are all scheduled to start redistributions near the end of the life of the 47th Parliament due to the passing of 7 years since their last. They will be deferred to the 48th Parliament if the 47th is dissolved before 25 July 2025. See Table 2 at the end of this paper which shows the date of their last redistribution.

Past and projected changes in states’ share

Western Australia

The rebasing of the population associated with the latest Census, will likely cause Western Australia’s entitlement to increase to 16 seats, gaining the seat it lost for the 2022 election and returning it to the same number of seats it had at the 2016 and 2019 elections. As Figure 1 shows, its share sits in the middle of the ‘16 seats’ range so a large change in its share would be needed to result in anything but 16.

 

Figure 1: Estimated representation entitlement for Western Australia

Estimated representation entitlement for Western Australia

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library

Victoria

The rebasing of the population by the Census and the COVID-19-related fall in net overseas migration will cause Victoria’s entitlement to decrease by one seat from the 39 contested at the 2022 election, to 38. In the previous edition of this paper the chances of Victoria losing a second seat was a possibility, but with the revised data this looks less likely.

If the determination results in Victoria being entitled to 38 seats, it will return to the number it held at the 2019 election.

 

Figure 2: Estimated representation entitlement for Victoria

Estimated representation entitlement for Victoria

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library

 

New South Wales

With a downturn in its already decreasing share of Australia’s population, as at March 2022 New South Wales has dropped from 47 to 46 seats. The projection in Figure 4 shows it will almost certainly be entitled to one less seat by the determination date.

 

Figure 4: Estimated representation entitlement for New South Wales

Estimated representation entitlement for New South Wales

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library


 

Queensland

Queensland has a slim chance of gaining a seat, though recent slower growth suggests this is less likely than Figure 3 suggests. The previous edition of this paper showed Queensland crossing the threshold into 31 seats, but the March 2022 figures have changed that. If next quarter’s growth is similar to either of the last two quarters, then the estimate for entitlement will be even further from the 30.5 line and therefore more likely that Queensland will remain on 30 seats.

 

Figure 3: Estimated representation entitlement for Queensland

Estimated representation entitlement for Queensland

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library

 

South Australia

Although not far under the threshold of 11 seats, South Australia’s entitlement looks stable and should remain at 10 seats at the next election.

Figure 5: Estimated representation entitlement for South Australia

Estimated representation entitlement for South Australia

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library

Tasmania

Even though it would be entitled to only 3 seats under the representation entitlement formula, Tasmania will retain its 5 seats because section 24 of the Constitution guarantees that each of the original states is entitled to at least 5 members.

 

Figure 6: Estimated representation entitlement for Tasmania

Estimated representation entitlement for Tasmania

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library

 

Special cases—the Territories

Due to the smaller populations of the 2 Territories, the number of people represented by each member would increase greatly if a territory were to lose a member via the entitlement calculation. To increase their likelihood of getting an extra member at future entitlement determinations, a ‘harmonic mean’ will be applied that gives them 2 members if their quotient is between 1.3333 and 1.5, and 3 members if their quotient is between 2.4 and 2.5.[12] Both Territories are safely above their respective thresholds (see Figures 7 and 8).


 

Australian Capital Territory

With a projected share of 2.62, the Australian Capital Territory will safely retain its 3 seats. As a territory, the range for 3 seats is between 2.4 and 3.5 (3.5 not shown on Figure 8).

 

Figure 7: Estimated representation entitlement for the Australian Capital Territory

Estimated representation entitlement for the Australian Capital Territory

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library

Northern Territory

The Northern Territory’s share is stable and with its entitlement at just over 1.4 it is safely within the range for 2 seats, which is between 1.333 and 2.4 (2.4 not shown in Figure 8).

 

Figure 8: Estimated representation entitlement for the Northern Territory

Estimated representation entitlement for the Northern Territory

Source: ABS, National, state and territory population (Canberra: ABS, 2022), calculations by Parliamentary Library

 

Conclusion

The Parliamentary Library’s population projections suggest that 3 redistributions—Western Australia, Victoria, and New South Wales—are expected to be triggered by the representation entitlement determination 12 months after the first sitting of the 47th Parliament. Based upon these projections, Western Australia is likely to gain a division and both New South Wales and Victoria may lose a division.

Based on the most likely entitlement outcomes, the House of Representatives will reduce by one seat to 150 seats at the next election, as there were from 2001 to 2016.

The scheduled redistribution of the Northern Territory should go ahead, but the scheduled redistributions of Tasmania, Queensland, Australian Capital Territory and South Australia will be deferred until the next parliament. There’s a remote chance of a gain of one seat for Queensland, which would trigger its redistribution in this parliament instead of being deferred to the 48th parliament.

A timetable showing the most recent and next predicted redistribution in each state and territory is shown in Table 2 below.

 

Table 2: Timetable of predicted electoral redistributions

State/territory Most recently determined Expected trigger for next redistribution Predicted start of next redistribution Parliament
NSW 26 February 2016 Entitlement change July/August 2023 (a) 47th
WA 2 August 2021 Entitlement change July/August 2023 47th
Vic 26 July 2021 Entitlement change July/August 2023 47th
NT 7 February 2017 7 years February/March 2024 47th
Tas 14 November 2017 7 years July/August 2025 (c) 48th
Qld 27 March 2018 7 years July/August 2025 (b) 48th
ACT 13 July 2018 7 years July/August 2025 (c) 48th
SA 20 July 2018 7 years July/August 2025 (c) 48th

(a) If, prior to February/March 2023, the Electoral Commission considers New South Wales’ entitlement will or may change, then its scheduled redistribution of February/March 2023 will be deferred to July/August 2023.
(b) If Queensland were to gain a seat, the entitlement change would trigger a redistribution in July/August 2023.
(c) Scheduled to commence within 12 months of the deemed expiration of the 47th Parliament, so will be deferred until after the first sitting of the next House of Representatives.

NOTE: The change in entitlements for Queensland and Victoria are both within 0.15 percentage points of a different outcome. The predicted December 2022 population is based on a simple linear annual increase. There are many ways to project future population that would result in entitlements different to those shown here. The previous edition of this paper used data as at December 2021 and predicted the possibility of different entitlements for Queensland and Victoria. The March 2022 figures made these outcomes less likely.

Due to the closeness of some states’ result, small fluctuations in future ABS ERP releases may change the results shown here. A change in one state’s share will, by definition, change the share in at least one other state at the decimal level, but might not change the rounding to the nearest integer and hence the number of seats.

 


[1].    Section 24 of the Australian Constitution refers to the ‘number of members’. In this publication, the term ‘members’ is used interchangeably with ‘seats’, as the two are intrinsically linked.

[2].    ABS, Methodology used in rebased population estimates, June 2021.

[3].    Addresses held by Medicare are used by the ABS to determine, in part, movements in interstate migration and the ABS has seen a ‘implausibly’ high number of moves in September and December 2021 quarters due to widespread updating of Medicare records as people get vaccinated for COVID-19.

[4].    ABS, Overseas migration, December 2021.

[5].     Australian Constitution, section 24 in particular.

[6].    Assuming a normal House of Representatives and half-Senate election, this will occur between August 2024 and May 2025.

[7].    For information on the redistribution process, see: Australian Electoral Commission (AEC), ‘Redistributions’, AEC website; D Muller, The process of federal redistributions: a quick guide, Research paper series, 2017–18, Parliamentary Library, Canberra, 2017. For the dates of all previous redistributions, see: AEC, ‘Redistribution dates since 1901’, AEC website.

[8].    Until otherwise determined, the expiration of the 47th Parliament is deemed to be 25 July 2025, the end of 3 years after the first sitting of the House of Representatives on 26 July 2022.

[9].    Commonwealth Electoral Act 1918, section 59.

[10]. A quota is ascertained by dividing the total population of the 6 states by twice the number of senators for the 6 states. The calculated number of members for each state and territory is then determined by dividing the population of the state or territory by the quota. The calculated number rounded to the nearest whole number determines the entitlement.

[11]. Australian Bureau of Statistics (ABS), National, state and territory population, ABS, Canberra, 2022, p. 2, accessed 26 September 2022. There is a lag of 6 months between the date to which the population estimates pertain and when they are published.

[12]. The Australian Electoral Commission has more information on determining the number of members for the territories in their  Calculating the representation entitlements of states and territories.

 

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