WHAT WAS CLAIMED
New Zealand's net government debt has more than doubled under the National-led coalition.
OUR VERDICT
False. A graph appearing to show debt doubling uses flawed methodology.
AAP FACTCHECK - New Zealand's government net debt has not more than doubled under the National-led coalition, despite claims in a graph on social media.
The graph misleadingly switches between three distinct net debt measures across different years, making debt appear to have spiked since the coalition took office in 2023.
Treasury data shows Core Crown Net Debt - the government's primary net debt measure - increased by 21 per cent between July 2023 and March 2026.
The claim is in a Facebook post featuring a graph showing government debt rising from roughly $70 billion when the coalition came to power in 2023 to more than $180 billion in 2026.
"NZ government net debt for the last 50 years," the caption reads.
A note on the graph cites the data source as the official financial statements published by the Treasury.
Other social media users shared the graph, including some who claimed it proved "right-wing" governments borrowed more than "the left".
However, Core Crown Net Debt has increased by about $32 billion under the National coalition government - from $155.3 billion to $187.8 billion - not by the $100 billion-plus figure suggested by the graph.
The graph also incorrectly depicts debt falling at the end of the previous Labour government's term, when it actually increased.
Ken Warren, a former chief accounting advisor at the Treasury and adjunct teaching fellow at Te Herenga Waka Victoria University of Wellington, said the recent trends depicted in the graph were incorrect.
Treasury time series data showed no such debt spike under the current administration and no dip during Labour's last term, he said.
The social media graph's errors appear to stem from its failure to account for historical changes in how government debt was measured, he said.
Various governments have changed the headline, or primary, debt reporting measure three times in recent years: in 2009, 2022 and 2024.
In 2009, the National government changed the definition of Core Crown Net Debt to exclude advances on loans, such as student debt.
This made the headline net debt figure appear slightly higher than it would have been using the pre-2009 measure.
Then in 2022, the Labour government changed the headline net debt measure from Core Crown Net Debt to an alternative called "Net Debt".
This new measure included the financial assets and debts of the New Zealand Superannuation Fund - a sovereign wealth fund designed to help fund superannuation payments.
A Labour government press release in May 2022 said the new Net Debt measure would make headline net debt appear significantly lower, but would make NZ's figure more internationally comparable "so that we can accurately compare ourselves against others".
In 2022, Core Crown Net Debt was $128.9 billion, but Net Debt was $61.9 billion, according to Treasury's time-series data ("Debt, Net Worth" worksheet).
Yet the social media graph appears to depict the pre-2009 Core Crown Net Debt measure until 2022, when it was $102.8 billion.
The graph then switches to the new Net Debt measure in 2023, which was $71.4 billion, making the debt appear to fall significantly at the end of Labour's term.
However, pre-2009 Core Crown Net Debt and Net Debt are two distinct measures.
Switching between them distorts the trend in government borrowing.
Using either measure consistently through 2023 shows that government debt actually increased significantly that year.
Under the pre-2009 Core Crown Net Debt measure, it rose by 20.5 per cent in 2023, while under the Net Debt measure, it increased by 15.4 per cent.
In 2024, the National-led coalition government (p6) reinstated the post-2009 measure of Core Crown Net Debt for its headline net debt figure.
The social media graph then switches a third time — to this reinstated Core Crown Net Debt measure — for 2024 and 2025, making debt appear to more than double under the National-led coalition.
However, the actual increase in government net debt was more modest.
Treasury data shows that between 2023 and 2024, it increased by 13 per cent under the newer Core Crown Net Debt measure, and by 15 per cent under the Net Debt measure.
In 2023, the government stopped reporting the pre-2009 Core Crown Net Debt measure.
Debt has climbed further since, but it has not doubled.
The Treasury's interim financial statement in May 2026 shows Core Crown Net Debt reached $187.8 billion by March 2026 (Table 1, p2).
Treasury's time series data includes three distinct net debt measures, each covering different periods: pre-2009 Core Crown Net Debt from 1972 to 2022, the newer Core Crown Net Debt from 1992 to 2025 and Net Debt from 2008 to 2025.
No single measure runs continuously from 1972 to 2025.
Regardless, none of the official measures matches the figures in the graph, which exaggerates government net debt across the 1970s, 1980s, 1990s and 2000s.
Mr Warren said the graph's author may have produced this result by converting the historical figures to 2025 dollars.
The social media graph appears to include a similar data mismatch in its depiction of net debt as a percentage of GDP.
Mr Warren said the general debt-to-GDP trends depicted by the graph appeared accurate up to about 2022, but the spike shown after 2023 was misleading.
A near-identical graph, with the same errors, that spread on social media in 2024 was shared by Labour finance spokeswoman Barbara Edmonds.
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