What is "national debt"?
National debt — formally Commonwealth Government Securities on issue — is the total amount the Australian Government has borrowed and not yet paid back. When the Budget runs a deficit (spending more than it raises in tax), the gap is funded by issuing bonds. Those bonds are the debt.
Heading into 2025-26, gross debt sits in the trillion-dollar range, with net debt projected by Treasury to rise across the forward estimates. That's the number you hear quoted on the news — but the number that actually shapes the Budget is the interest bill.
Why the interest bill matters more than the headline number
Debt itself isn't paid back in any given year — it's rolled over. What the Budget must pay each year is interest. In 2025-26 that interest bill is one of the fastest-growing line items in the entire Budget, sitting alongside the NDIS, aged care, health and defence as a major call on revenue.
Every dollar spent servicing debt is a dollar that can't be spent on a hospital bed, a classroom, a Medicare rebate, or a tax cut. That's the trade-off. It isn't ideological — it's arithmetic.
The trade-offs, line by line
When commentators argue about "fiscal responsibility" vs "investing in services", this is what they're really arguing about. A higher interest bill squeezes the room available for:
- Health — Medicare, public hospitals, the PBS, mental health funding.
- Education — schools funding, university places, fee-free TAFE.
- Cost-of-living relief — energy rebates, rent assistance, childcare subsidies.
- Tax cuts — lower taxes mean less revenue to cover both services and interest.
- Infrastructure and defence — long-term capital projects that themselves are often debt-funded.
You don't have to take a side to see the constraint. More debt servicing = less fiscal room. Less debt servicing = either higher taxes, lower spending, or both.
Is Australia's debt actually high?
Compared with most other advanced economies — the US, UK, Japan, much of Europe — Australia's debt-to-GDP ratio is on the lower end. That's the case Treasury and the RBA usually make when they describe the Budget position as "sustainable".
The counter-argument is that lower-than-others isn't the same as low, and that rising interest rates make even a modest debt load more expensive to carry year after year. Both things can be true at once.
What this means for the 2025-26 Budget
Every measure in the 2025-26 Budget Papers — new spending, tax changes, "savings" — interacts with debt. A measure that adds to the deficit grows the debt and, eventually, the interest bill. A measure that reduces the deficit does the opposite.
That's why we let you vote on every measure individually. The national conversation usually happens at the slogan level ("more spending" / "lower taxes"). The actual Budget is hundreds of specific decisions, each with a fiscal impact.
Have your say
The clearest way to engage with the debt question isn't to debate the headline number — it's to look at the line items it's funding and decide which ones you'd keep, cut, or grow.