Offshore carbon credits are a $5 billion bill the Crown hasn’t booked

Strip away the moral language in Climate Action Tracker’s latest briefing and what remains is an accounting problem. New Zealand has a 2030 Paris target, a domestic policy mix that will not hit it, and a plan to cover the gap with international credits that nobody has formally budgeted for. That is not just a climate story. It is a fiscal one, and business will end up carrying part of the bill, through tax, regulation or both.

The world’s heaviest reliance on bought credits

The independent research group’s pre-election briefing concludes that current policy cannot meet New Zealand’s 2030 commitment without offshore units, and that the share required is by far the largest in the world. Under Article 6 of the Paris Agreement, traded credits are meant to supplement domestic cuts once a country is on a credible trajectory, not replace them. CAT also warns there is no guarantee enough high-quality credits will even be available at the volumes New Zealand needs.

Those volumes are large. Treasury estimates the country must secure 85-96 million tonnes of offshore mitigation over 2021-2030, more than New Zealand’s entire annual emissions in 2024. Under current settings, CAT puts the country 27-33% above a 1.5C-compatible level by 2030, with the gap widening further by 2035.

Treasury has already put a price on it

This is not activist arithmetic. Treasury’s own June 2026 paper estimates the offshore bill at $4.4-5 billion for 2030, plus up to $1.6 billion more for 2035. Combined, that is a $4.6-6.6 billion exposure.

In 2023, Treasury’s Climate Economic and Fiscal Assessment carried a far wider range of $3.3-23.7 billion. The narrowing is not good news in disguise. It reflects assumptions hardening as 2030 gets closer, not the problem shrinking. And because the estimate depends on carbon prices in a thin international market, the risk sits mostly on the upside if New Zealand ends up buying late and in bulk.

A liability that officially isn’t one

Here is the part almost nobody outside Wellington is watching. In an Official Information Act response released in February 2026, Treasury concluded there was no legally enforceable obligation requiring the Crown to recognise the offshore mitigation cost as a liability in its financial statements, because the Paris commitment is not binding in the relevant legal sense. So a multi-billion-dollar expected outflow lives in briefings and working papers, but not on the books.

Critics have been making this point for years. Back in 2024, Wendy McGuinness of the McGuinness Institute argued the exposure should be booked, because the current treatment quietly favours sending money overseas over investing at home. “Imagine the leverage this would give New Zealand business,” she said at the time. “Because the counterfactual is we give all this money overseas, rather than transition our economy.” A 2024 Motu research paper likewise questioned whether leaning heavily on international credits was sound economic policy or a long-term vulnerability.

For a government that campaigns on fiscal discipline, an unbooked bill of this size should be uncomfortable. Prudent firms disclose contingent liabilities. The Crown should hold itself to the same standard.

Two promises that cannot both hold

Prime Minister Christopher Luxon said in June that the government will do everything it can to honour Paris, but “we ain’t shutting down farms and we certainly aren’t sending billions of dollars offshore”. On Treasury’s own numbers, those commitments are mathematically incompatible. Without much deeper domestic cuts, the target is met by writing cheques abroad, or it is missed.

The government’s record is not empty. Climate Change Minister Simon Watts points to total emissions falling 2.9% in the year to June 2026, a sharp drop in emissions intensity and a surge in renewable generation. His argument that pricing farmers out of existence would simply shift production offshore is a fair one, and backing agricultural technology is a defensible bet. But a single good year does not close a gap measured in tens of millions of tonnes.

What business should price in now

There are three plausible paths, and none is free. A future government buys the credits, putting billions of pressure on a tight Budget that ultimately lands on taxpayers and spending priorities. Or it decides the offshore bill is unacceptable and re-regulates at home, revisiting agricultural pricing, tightening the ETS or leaning harder on transport and industry. Or New Zealand misses its target and absorbs the reputational cost with trading partners that increasingly treat climate credibility as a condition of market access.

With voters about to choose a government, the honest question for every party is which of those paths it is choosing. Businesses planning capital spending, land use or emissions-heavy operations over the next five years should assume the bill arrives one way or another. The only thing currently missing is the line in the accounts that admits it exists.

Sources

• RNZ: NZ’s rollback of climate policies ‘staggering’ – Climate Action Tracker (2026-10-30)
• Climate Action Tracker: New Zealand, three years of systematic climate policy rollbacks (2026-10-28)
• Treasury Paper 26/01: New Zealand’s Nationally Determined Contributions – Potential fiscal costs associated with offshore mitigation (2026-06)
• RNZ: Government facing up to $5 billion bill over carbon credits, Treasury reveals (2026-06-11)
• Treasury: OIA response 20250807 – Advice on offshore mitigation costs and fiscal implications of NDC1 (2026-02)
• RNZ: The woman fighting climate change with accounting (2024-05-03)
• Motu: Think globally, act cooperatively – Progressing offshore mitigation for Aotearoa New Zealand (2024-10)