Federal redistributions kick off

Now that the Parliament has officially opened for its first sitting after the federal election, we’re off to the races with redrawing the electoral map for the next federal election, expected in 2028. No rest for the wicked.

The redistributions in this parliamentary term are expected to be much less dramatic than those seen in the previous term. It seems unlikely that any state will see a change in their entitlement of seats in the House of Representatives. If so, the only redistributions will be the four triggered due to seven years passing since the previous redistribution. Conveniently, this will mean that the four states and territories that did not redraw their boundaries will get a new map in this term, while the other four will be left alone.

In this post I will run through the timing of these processes, and the data we now have to give us a hint about how these redistributions will play out.

Under Australian law, the federal electoral boundaries for a state or territory will be redrawn for one of three reasons:

• A change in that state’s entitlement to seats in the House of Representatives
• Seven years has passed since the conclusion of the last redistribution.
• The number of electors in at least one third of divisions deviates from the average enrolment by more than 10% for at least two months.

The third criteria has never been triggered, thanks to the AEC’s strict rules on drawing boundaries (more on that later).

Under the second rule, there are four jurisdictions due to commence redistributions this year. Queensland, South Australia, Tasmania and the Australian Capital Territory all completed their last redistributions in 2018. The seven-year mark was reached earlier this year for Queensland and Tasmania, but those redistributions were deferred until after the federal election. South Australia and the ACT have both reached the seven year mark this month. So they should all start very soon.

The other question is whether the entitlement of seats per state will change at all. This calculation will be conducted one year after the first sitting of Parliament (July 2026) using the latest ABS population estimates at the time, which will be the December 2025 data. This data is published every three months, so we can track the trajectory.

This chart shows the quarterly ABS population estimates from March 2020 to December 2024 (the latest currently available). It shows how much each state’s population is above or below their current seat count.

There is no state in any danger of currently losing a seat. New South Wales is on a downward trajectory that could cost the most populous state its 46th seat prior to the 2031 election, but not in the next year. South Australia is also on a downward trend.

Queensland is getting relatively close to gaining a 31st seat, but it doesn’t look like it will be enough. Queensland currently has 30.36 quotas of population, so needs another 0.14 quotas. It has taken over two years for Queensland’s population to grow by 0.14 quotas.

If there is any doubt about whether Queensland’s seat entitlement will change, the AEC has the option of deferring Queensland’s redistribution until the decision is clear. I don’t think Queensland will gain a 31st seat, but I don’t know if that deferral will happen.

All the same, that means that it’s just these four jurisdictions (most of them relatively small ones) being redrawn.

While in 2022-25 there were redistributions affecting 102 electorates (with 100 in states where the seat count changed), in this parliament that number will likely be just 48 (and none where the state’s count changes).

This parliamentary term would thus be only the second term since at least the 1993-96 team where there was no change to the seat entitlement for a state or territory.

This should mean that the scale of the changes will be reduced. It will also allow me to prepare my election guides for the unredistributed two thirds of the country much earlier than for the redistributed parts.

So, what is likely to happen in these four jurisdictions? For this next section I will post the current (June 2025) enrolment statistics for seats in each state.

Federal redistributions require divisions to be drawn within 10% of the average as of the current day, but more importantly they must be drawn within 3.5% of the average based on projected enrolments three-and-a-half years in the future. We don’t yet have projections, so I can only do analysis on current enrolment data.

Let’s start with Queensland, with its 30 electorates. This should not be confused with the redrawing of Queensland’s 93 state electorates, which has just recently commenced.

This map shows how much each seat deviates from the average: red for under-average seats, blue for over-average.

The most distinctive feature is a band of seats around South-East Queensland that are well over quota: Wright, Blair, Longman and Fisher are all over 10% over quota. Fadden and Forde, which border each other on the edge of Brisbane and the Gold Coast, are not far behind.

To simplify the story, this table shows how much each region of the state deviates from the average.

The 20 seats of south-east Queensland are collectively about one third of a seat over quota, but this is not evenly distributed. Indeed six seats in the outer south-east (which includes Ipswich, the Sunshine Coast and some other areas) is more than half a seat over. The Gold Coast is roughly in line, while Brisbane is almost a third of a seat under population.

This points towards Brisbane seats having to expand outwards to absorb that surplus population in those outer suburban seats. In the Brisbane area proper, the seat of Brisbane is slightly over quota, and Petrie is substantially over quota, but every other seat is below average. Moreton is particularly below average.

Outside of the south-east, just Hinkler has an above-average population. No seat has a particularly large shortfall, but it just adds up over the ten seats.

The same outer-suburban trend can be seen in South Australia.

Spence, in outer northern Adelaide, is 6.6% over quota, while Mayo is 6.3% over.

Hindmarsh is pretty spot on the average, while the other seven seats are all under quota. Makin is particularly under quota, by 5.8%.

The seven seats in urban Adelaide bounded by Spence and Mayo are pretty much exactly 10% under quota, so they should be able to absorb most of the surplus population in Mayo and Spence, although they are likely to be projected to grow faster than the two regional seats of Grey and Barker.

Tasmania’s new electoral map will apply to state and federal elections, following the recent Tasmanian state election.

The main story in Tasmania is the significant population shortfall in Clark, where enrolment is 9.9% below the average.

Braddon is slightly over quota and Bass is slightly under, but the two cancel each other out. Franklin is slightly over quota, but Lyons is significantly over quota.

It seems likely that this imbalance can be solved by Clark expanding further into the Hobart suburbs, in particular taking in parts of the southern end of Lyons.

The options get simpler for states with a smaller number of electorates. The ACT has just three seats.

The southern electorate of Bean is substantially over quota. Canberra has the biggest shortfall of voters, while Fenner is also slightly under. The exact changes would be dictated by the projections, but it’s likely Canberra will need to expand towards Woden to restore the balance.

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