Australia's parliament is likely to grow for the first time in 40 years

Australia's parliament is likely to get larger as the government canvasses possibilities for expanding the number of MPs and moving to fixed or four-year terms.

The parliament's joint committee on electoral matters has been tasked by Special Minister of State Don Farrell to examine whether more politicians should represent voters in the House of Representatives and Senate.

It will also explore sending Australians to the polls in fixed cycles, rather than on a date determined by the current prime minister, and the possibility of four-year terms.

It is the same process Senator Farrell followed last term to look at regulations on political donations, reforms that were later adopted.

Senator Farrell has argued the increase in Australia's population warrants a discussion.

"But the Australian people might say we don't want a bar of this, we're happy with the existing numbers of MPs, and that could be the end of it," Senator Farrell told Senate estimates late on Tuesday evening.

The number of MPs in the House of Representatives last substantially increased in 1984, when Bob Hawke was prime minister.

At the time, Australia's population had reached 16 million people and electorates contained 75,000 voters.

Since then, Australia's population has boomed to 27 million and is projected to hit 29 million ahead of the next federal election, due in 2028, and each electorate is home to around 120,000 voters.

Senator Farrell told estimates that MPs, and their staff, were now being required to do more work than ever to service their constituents and it was about time to consider an increase.

"We don't have a particular number in mind. We've raised the issue for consideration, I think it's a worthy issue to consider and we've sent it off to the body that always examines this," he said.

He said the political donation regulations investigated by the joint committee and adopted in the last term of parliament were good changes.

"Whatever changes we bring to the next parliament, I hope will be just as good," Senator Farrell said, before clarifying that an increase would not necessarily be adopted before the next election.

But the Coalition has already dashed any hope of bipartisanship on the matter, with James McGrath, the shadow special minister of state, questioning the government's priorities.

"I find it extraordinary that we are wasting taxpayer resources and time on this when the government should be focused on fixing the healthcare crisis, the cost-of-living crisis, and the self-made housing crisis currently crippling our economy and Australians," he told the ABC.

Increasing the number of MPs can be done via legislation but a large expansion would require the parliament to balance out the number of senators, under a provision of the constitution known as the "nexus".

It requires the number in the chamber to be, "as nearly as practicable", twice the number of senators — and involves a mathematical equation to allocate the number of electorates. Each state is guaranteed five MPs.

Doubling the number of territory senators was recommended during the last term of parliament. The government is keen to adopt the proposal but is waiting to see if it can be done as part of a wider expansion.

The Australian Electoral Commission told senators on Tuesday night it had not yet turned its mind to the possibility of redrawing the entire electoral map.

"Of course, it would depend on what the number is for a new parliament. But it's possible that we may well need to do a redistribution for the six mainland states prior to any implementation," commissioner Jeff Pope said.

That process, if run like a typical redistribution, would be a "significant undertaking", Mr Pope added.

Prime Minister Anthony Albanese has consistently expressed his support for adopting four-year terms like the states.

But doing so would require a referendum, and he has repeatedly rejected the idea of holding a poll during this term after being burned by the failed Voice referendum.

It is understood there is a possibility the government could push forward with fixed terms without the need for a referendum by opting to keep term lengths at the current three-year period.

But that would depend on the advice from constitutional experts, who are expected to give evidence to the inquiry, which is due to hand back its interim report mid-2026.

The joint parliamentary inquiry is expected to kick off hearings as early as next week.