Money · Credit · New Zealand · Part 18
How much debt can New Zealand actually carry?
There is no single magic debt-to-GDP number that tells us when a country is safe, reckless or bankrupt.
We often talk about government debt as though there is a line on the floor.
Forty per cent is safe.
Fifty per cent is dangerous.
Seventy per cent means crisis.
But sovereign debt does not work that neatly.
Two countries can have the same debt-to-GDP ratio and very different levels of risk.
One may have strong growth, low borrowing costs, long debt maturities, credible institutions and a reliable tax base.
The other may face weak growth, high interest costs, short-term refinancing pressure, foreign-currency liabilities and collapsing investor confidence.
The ratio alone cannot tell us the whole story.
Debt capacity is not a number. It is a relationship between obligations, income, interest costs, institutions, assets, market confidence and shocks.
Start with the current New Zealand position
The latest Treasury interim financial statements available as at 29 August 2026 put net core Crown debt at $186.0 billion, or 41.3% of GDP, at 31 May 2026.
Treasury — Interim Financial Statements to 31 May 2026 ↗
Budget 2026 forecasts the ratio at 42.4% for 2025/26, rising to a peak of 46.1% in 2027/28 before declining to 44.4% in 2029/30.
Treasury — Budget Economic and Fiscal Update 2026 ↗
Those figures tell us where the debt ratio is.
They do not, by themselves, tell us the maximum New Zealand could borrow.
There are actually four different debt questions
When someone asks “How much debt can New Zealand carry?”, I think we should separate four questions.
1. How much can the market currently lend us?
2. How much debt can the Crown service over time?
3. How much debt is prudent if we want room for the next shock?
4. How much debt produces more value than it costs?
Those answers are not necessarily the same.
A country may be capable of borrowing more than it would be wise to borrow.
“The market will lend it” is not the same test as “the country should borrow it.”
Debt-to-GDP is useful because it compares debt with the economy supporting it
$200 billion of debt sounds enormous.
But nominal dollars without context tell us little.
A larger economy has a larger tax base and greater capacity to service a given nominal debt stock.
That is why debt is usually compared with GDP.
Debt-to-GDP is not a perfect measure of solvency, but it tells us whether the debt burden is growing faster or slower than the economy supporting it.
If nominal debt grows by 3% while nominal GDP grows by 5%, the debt ratio can fall even though the dollar amount of debt rises.
If debt grows persistently faster than GDP, the ratio rises.
The interest rate-growth relationship matters
Treasury's work on public-debt dynamics identifies four important drivers of the debt ratio:
the primary fiscal balance,
real GDP growth,
real interest rates,
and exchange-rate effects where foreign-currency debt is relevant.
Treasury — Public Debt Dynamics in New Zealand ↗
The basic intuition is powerful.
If the economy's income base grows faster than the effective interest burden on the debt, the debt ratio is easier to stabilise.
If interest costs rise faster than growth, progressively larger primary surpluses may be needed to prevent the debt ratio from climbing.
Debt is easier to carry when the economy grows faster than the burden attached to the debt.
But growth cannot rescue permanent deficits forever
There is a seductive version of that argument.
If GDP keeps growing, perhaps debt can simply keep growing too.
Sometimes the ratio can remain stable while nominal debt rises.
But the primary balance still matters.
Treasury's debt-dynamics work found that New Zealand's primary balance — revenue excluding borrowing compared with non-interest spending — has historically been the largest driver of changes in public debt.
Persistent structural deficits eventually overwhelm favourable growth-interest dynamics.
That is why Budget 2026's estimate that around 60% of the 2025/26 OBEGALx deficit is structural matters.
Treasury — Structural fiscal position, BEFU 2026 ↗
Debt service can become the constraint before the debt ratio does
Imagine two governments each have debt equal to 50% of GDP.
One pays an average effective interest rate of 2%.
The other pays 7%.
The second government has to devote far more revenue to servicing the same debt ratio.
That matters because interest payments compete with every other use of public money.
Health.
Education.
Infrastructure.
Tax reductions.
Emergency response.
Treasury says the rise in superannuation, healthcare and finance costs explains a substantial share of the increase in core Crown expenses as a percentage of GDP since 2018/19.
Treasury — Core Crown expenses and finance costs ↗
So I would always track interest expense relative to Crown revenue alongside debt-to-GDP.
Refinancing risk matters too
Government debt is not one giant mortgage maturing on one date.
It is a portfolio of bonds and short-term securities with different maturities.
When bonds mature, the Crown may repay them from cash or issue new debt to refinance them.
If too much debt matures in a short window, market disruption or a spike in interest rates can become expensive.
New Zealand Debt Management therefore deliberately spreads issuance across maturities and manages refinancing risk.
As at May 2026, the average weighted term to maturity of the New Zealand Government Bond portfolio was around 7.5 years.
New Zealand Debt Management — 2026/27 Funding Strategy ↗
Gross bond issuance is not the same thing as new debt
This distinction is important.
NZDM plans $34 billion of gross New Zealand Government Bond issuance in 2026/27.
That does not mean net Crown debt automatically rises by $34 billion.
Gross issuance also finances bonds that mature and need refinancing, as well as the Crown's cash requirements.
NZDM — Government Bond Programme Update, BEFU 2026 ↗
Whenever we talk about “government borrowing”, we therefore need to distinguish:
gross issuance,
net new borrowing,
and the stock of debt outstanding.
Investor demand is part of debt capacity
A government needs reliable access to buyers for its securities.
New Zealand Debt Management's objective is to minimise the Crown's borrowing costs over the long term while ensuring ongoing access to debt markets and managing risk.
Its strategy emphasises transparency, consistency, liquid benchmark bond lines and a broad investor base.
This matters because investor confidence affects the interest rate the Crown must offer.
A country that repeatedly surprises markets, hides liabilities or appears unwilling to stabilise its fiscal position can increase its own borrowing costs.
And higher borrowing costs can then worsen debt dynamics further.
Borrowing largely in New Zealand dollars reduces one risk
New Zealand's primary government funding instruments are New Zealand-dollar Government Bonds and Treasury Bills.
NZDM maintains a foreign-currency issuance facility, but says it has not used its long-dated foreign-currency EMTN programme since 2004 and currently has no plans to do so.
NZDM — Funding instruments and foreign-currency programme ↗
Borrowing predominantly in the domestic currency avoids a major risk faced by governments that owe large amounts in a currency they do not issue.
But that does not make debt costless.
The Crown still has to pay interest, refinance maturities and maintain investor confidence.
The Crown's assets matter
Part 14 established that the Crown does not only have debt.
It also owns hundreds of billions of dollars of financial, commercial and social assets.
That matters when assessing overall balance-sheet strength.
But we should not make the opposite mistake and assume every Crown asset can easily service debt.
A hospital is valuable but illiquid.
A school cannot simply be sold during a recession to meet bond maturities.
This is why Treasury also uses financial net worth and net debt measures when assessing resilience.
Treasury — Investment Statement 2025 ↗
So where does the 50% figure come from?
Treasury's 2025 Investment Statement recommended that, in normal times, New Zealand target small operating surpluses and keep net core Crown debt below 50% of GDP.
Its reasoning was not that 50.1% causes a crisis.
The recommendation was designed to preserve enough borrowing capacity to respond to shocks and economic cycles while still allowing debt to finance worthwhile long-term investment where headroom exists.
Treasury — Recommended debt ceiling and fiscal buffers ↗
This is an advisory prudence benchmark.
It is not a technical maximum borrowing limit.
A prudent ceiling is deliberately lower than the point where lenders finally refuse to lend.
The Government currently uses a different operating objective
The current Government's long-term fiscal objective is to reduce net core Crown debt below 40% of GDP and then maintain it within a 20% to 40% normal-times range, subject to economic shocks.
Treasury — Current Government fiscal strategy ↗
Again, that is a policy choice about prudent headroom.
It should not be confused with an economic law saying 39.9% is safe and 40.1% is unsafe.
The important debate is what amount of buffer New Zealand should preserve given its risks and investment needs.
New Zealand has good reasons to value a meaningful buffer
We are a small, open economy.
We are exposed to earthquakes, floods and other natural hazards.
Our export earnings can be affected by global commodity markets and trade conditions.
We rely on international capital markets.
We have an ageing population and long-term health and superannuation pressures.
And major infrastructure renewal needs are already visible.
Those risks argue for keeping room to borrow when circumstances deteriorate.
If debt is pushed to its practical limit during ordinary times, the next emergency can force abrupt tax increases, spending cuts or much more expensive borrowing.
But too much caution can also be costly
There is a mirror-image risk.
A government can preserve an immaculate debt ratio while allowing:
hospitals to deteriorate,
water networks to fail,
electricity bottlenecks to constrain investment,
or transport infrastructure to become increasingly expensive to repair.
That can weaken the asset side of the national balance sheet and reduce future productivity.
So “keep debt low” cannot be the only fiscal objective.
Fiscal headroom has value. So does using some of that headroom well.
The quality of the borrowing changes the answer
Suppose New Zealand adds five percentage points of GDP to debt.
Scenario A:
the money finances recurring expenditure with no permanent revenue source.
Scenario B:
the money finances high-value electricity, water and health infrastructure that passes rigorous investment tests and leaves durable assets.
The debt ratio is the same.
The balance-sheet and economic consequences are not.
This does not make Scenario B automatically good.
The projects can still be overpriced, badly delivered or inflationary.
But it shows why debt quantity and debt purpose need to be considered together.
The speed of borrowing matters
A country may eventually be able to carry more debt without being able to absorb a very large increase immediately.
Rapid issuance can:
increase borrowing costs,
test market capacity,
concentrate future refinancing,
and coincide with real-resource constraints in the domestic economy.
So debt capacity is partly a stock question and partly a flow question.
Stock: how much debt is outstanding?
Flow: how quickly are we adding to it and how much new issuance must markets absorb?
Contingent liabilities count even before they become debt
Government guarantees, disaster obligations, Crown-entity risks and other contingent exposures may not all appear in net core Crown debt today.
But they matter to real fiscal capacity.
If a Crown institution fails and requires recapitalisation, or if an explicit guarantee is called, the liability can migrate onto the Crown balance sheet quickly.
That is why Parts 10 and 11 insisted that public-investment institutions cannot be used to hide risk outside headline debt measures.
My debt-capacity dashboard
If I wanted to know whether New Zealand could prudently carry more debt, I would track at least these measures together:
1. Net core Crown debt as a percentage of GDP.
2. The operating and primary fiscal balance.
3. Interest and finance costs relative to Crown revenue.
4. Nominal GDP growth relative to the effective interest rate on debt.
5. Bond maturity and refinancing profile.
6. Investor demand and borrowing spreads.
7. Crown financial net worth and liquid assets.
8. Contingent liabilities and guarantees.
9. The quality of the assets or outcomes financed by new debt.
10. Remaining headroom for severe economic or natural-disaster shocks.
Then I would stress-test it
What happens if:
borrowing rates rise two percentage points?
GDP growth is weaker for five years?
a major earthquake requires tens of billions of dollars?
the exchange rate falls sharply?
the operating balance returns to deficit?
a large Crown guarantee is called?
or investor demand weakens?
A debt level that appears manageable only under the central forecast may not be prudent.
Debt capacity should be measured against the bad years, not just the expected ones.
So how much debt can New Zealand carry?
There is no defensible single number.
We can say that Treasury has assessed below 50% of GDP as a prudent normal-times ceiling in its 2025 balance-sheet work.
We can say the current Government has chosen a tighter long-term target range of 20% to 40% once debt is brought below 40%.
We can say the current forecast peaks at 46.1%.
But none of those facts means the Crown becomes unable to borrow at the next percentage point.
The practical capacity changes with interest rates, growth, fiscal balances, investor confidence, maturity structure, assets and the shocks we need to remain capable of absorbing.
My conclusion
The right debt question is not:
What is the maximum number?
It is:
How much debt can New Zealand service through a bad economic cycle while preserving market confidence, essential public services and enough capacity to respond to the next shock?
Then there is a second question:
Is the thing we want to borrow for valuable enough to use some of that capacity?
Those two questions belong together.
“More debt is possible” is a statement about capacity. “More debt is prudent” is a judgment about risk, purpose and what we need to preserve for tomorrow.
Next
That brings us to another part of public finance that is often misunderstood:
Who actually owns New Zealand government debt?
Part 19 will follow government bonds from issuance to investors and examine banks, KiwiSaver funds, pension funds, overseas investors, the Reserve Bank, secondary markets, interest payments and what it really means when people say “the country owes money”.
Primary sources
Treasury — Interim Financial Statements to 31 May 2026 ↗
Treasury — Budget Economic and Fiscal Update 2026 ↗
Treasury — He Puna Hao Pātiki: Investment Statement 2025 ↗
Treasury — Public Debt Dynamics in New Zealand ↗