While attention is focused on economists finding a $500 million-dollar-a-year hole in National's tax plans, a similar-sized hole in climate costings is hiding in plain sight - and it applies to Labour, too.

The gulf was highlighted in Treasury's pre-election look at the Government's books which does not include the cost of meeting New Zealand's international climate target under the Paris agreement.

Asked how they would pay, the Labour and National leaders have given unclear answers.

RNZ Climate Change Correspondent Eloise Gibson spoke to Ingrid Hipkiss.