How often are electoral boundaries reviewed?

Electoral boundaries in Australia are reviewed at least every seven years and more often if seat numbers change or if many existing electorates have drifted significantly from the average voter count. The triggers and process are set by the Commonwealth Electoral Act 1918 for federal electorates, with equivalent state and territory laws covering state and territory electorates.

Three triggers can prompt a federal redistribution. First, the constitutional requirement under section 24: if the Statistician's calculation of the state's entitlement to seats changes (usually because of relative population growth or decline), a redistribution is triggered to redraw the boundaries with the new seat number. Second, the seven-year rule: every state and territory must have a redistribution at least every seven years since its last redistribution, regardless of whether boundaries need to change substantially. Third, the malapportionment rule: if more than one-third of the electorates within a state have drifted more than 10 per cent away from the average enrolment, a redistribution is triggered.

Recent federal redistributions include New South Wales (2024 to 2025, losing one seat), Victoria (2024 to 2025, gaining one seat), Western Australia (2025), and Australian Capital Territory (2025 to 2026, gaining one seat). The 2024 to 2025 redistributions responded to population growth in Victoria and the ACT relative to New South Wales, reflecting the continuing shift of population toward southern and capital territory Australia.

The redistribution process takes about 12 to 18 months from start to finish. The Augmented Electoral Commission must call for suggestions at the start, then issue a draft, then invite objections, then hold public hearings, then publish a revised draft if needed, before issuing final boundaries. Each stage is open to public participation, with submissions and objections accepted from any Australian, political party, community group, or interested organisation. The final boundaries take effect at the next federal election after they are gazetted. New South Wales redistributions in particular often produce political effects, shifting safe seats to marginal and vice versa.