Parliament's Hidden Price Tag: How 38 Extra Seats Will Cost Taxpayers and Dilute Accountability

A proposal to expand the Australian Parliament by 38 members — a 17 per cent increase in the House of Representatives and a boost to the Senate — has been quietly costed by the Parliamentary Budget Office, and the numbers land with a thud. Recurrent and capital costs, including modifications to Parliament House itself and the full apparatus of entitlements that follows each new parliamentarian through the door, will run for decades. The proposal, put to the PBO by Liberal Senator James McGrath, would take effect from 1 July 2028. What it would actually deliver is a separate question from what it costs, and the two are worth examining together.

Population growth is a real pressure — but it doesn't settle the question

The case for expansion rests on a genuine problem. The principle of proportional representation requires that House of Representatives seats grow roughly in line with population, and Australia's population has grown substantially. A parliament sized for 20 million people was always going to feel undersized for 27 million. Electorates have grown larger, casework loads heavier, and the argument that each member can adequately represent a constituency of 110,000 or more people is not a trivial one. These are real pressures and the proposal is not without intellectual grounding.

But the mechanism matters as much as the motivation. When the people voting on whether to expand parliament are the same people who stand to benefit from that expansion, through more colleagues, more committee positions, more staff, more influence allocated across a larger chamber, you do not have a neutral cost-benefit assessment. You have a structural conflict of interest with no equivalent in the private sector. A company considering whether to double its executive team faces a board that answers to shareholders, a market that can punish poor capital allocation, and analysts who will notice. Parliament faces none of these. The feedback loop runs through elections held years apart, on agendas crowded with housing costs and interest rates, where the size of the legislature is rarely the deciding issue.

The incentive structure biases every parliament towards its own growth

This is the core of the problem. Not that the individuals involved are acting in bad faith, but that the incentive structure produces a systematic bias towards institutional expansion that no single vote corrects. Every new seat brings a salary, a staff allocation, an office budget, travel entitlements, superannuation, and a lifetime of post-parliamentary benefits. The PBO costing captures these flows over the forward estimates, but the real cost compounds across the life of the Parliament and the careers of the people filling those seats. Parliamentary expenses are not discretionary in the way a government programme can be defunded. They are structural.

The feedback loop runs through elections held years apart, on agendas crowded with housing costs and interest rates, where the size of the legislature is rarely the deciding issue.

The accountability argument cuts the same way. The standard case for a larger legislature is that more representatives means more scrutiny, more voices, more diverse views feeding into the chamber. It is a reasonable theory. The evidence for it is thinner. Australia already has two houses, active committees, a well-resourced independent auditor, and a Parliamentary Budget Office that produces exactly the kind of transparent costing we are reading now. What it has consistently struggled to produce is executive accountability that bites. Question Time is a performance. Senate estimates is where real scrutiny happens, and it happens now, before any expansion. Adding 38 members does not obviously strengthen the weakest parts of the accountability chain. It adds more people to a system whose bottlenecks are structural, not numerical.

More members means less leverage for each one

There is also a simple dilution effect worth naming plainly. A parliament of 264 members distributes attention, media oxygen, and institutional memory across a wider surface area. The crossbenchers who have wielded genuine leverage in recent parliaments did so because their votes were scarce and coveted. A larger chamber with more members means more people competing for the same finite amount of public attention and executive engagement. That does not automatically make parliament more powerful. It may make each individual member less so.

None of this means the proposal is indefensible. Population growth is real, electorate sizes are genuinely large, and there is a legitimate conversation to be had about democratic representation at scale. But that conversation needs to happen honestly, with the costs on the table and the incentive structure acknowledged. The PBO has done the first part. The second part is a question of political honesty that the institution being asked to vote on its own expansion has a structural difficulty answering.

The price tag on that empty seat is real. So is the question of who put it there, and why.

Sources

Parliamentary Budget Office — Cost of increasing the size of Parliament

Frequently Asked Questions

How much will expanding the Australian Parliament cost taxpayers?
The Parliamentary Budget Office costed the proposal in April 2026, finding it would impose recurrent costs — salaries, staff, entitlements, and office budgets — plus capital works to modify Parliament House. The draft does not publish the headline figures, but the PBO costing is publicly available at the link provided.

Why is Parliament being expanded and when would it take effect?
The proposal, put to the Parliamentary Budget Office by Liberal Senator James McGrath, would expand the federal parliament from 226 to 264 seats — a 17 per cent increase in the House of Representatives plus a Senate boost — taking effect from 1 July 2028. The stated rationale is population growth: Australia's electorate sizes have increased substantially as the population grew from roughly 20 million to 27 million.

Does a bigger parliament actually improve democratic accountability?
The evidence is thinner than the theory. Australia already has two houses, Senate estimates hearings, an Auditor-General, and a Parliamentary Budget Office — and its persistent accountability gap lies in executive scrutiny, not the number of members. Adding 38 seats does not obviously fix the structural bottlenecks where accountability actually breaks down.

Why is Parliament voting on its own expansion a conflict of interest?
Every new seat brings salaries, staff allocations, office budgets, travel entitlements, superannuation, and post-parliamentary benefits — meaning the people deciding whether to expand the institution are the same people who stand to gain from that expansion. Unlike a corporate board that answers to shareholders, parliament faces no market discipline and no direct cost if the decision proves poor value.

Would more crossbenchers in a larger parliament have more or less influence?
Likely less, on balance. Crossbench leverage in recent Australian parliaments has depended on votes being scarce and coveted by the executive. A larger chamber distributes attention and bargaining power across more members competing for the same finite executive engagement — which may reduce rather than increase each individual member's influence.